/* bcm2835.c
// C and C++ support for Broadcom BCM 2835 as used in Raspberry Pi
// http://elinux.org/RPi_Low-level_peripherals
// http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
//
// Author: Mike McCauley
// Copyright (C) 2011-2013 Mike McCauley
// $Id: bcm2835.c,v 1.27 2019/07/22 23:04:24 mikem Exp mikem $
*/


#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>

#define BCK2835_LIBRARY_BUILD

#include "bcm2835.h"

/* This define enables a little test program (by default a blinking output on pin RPI_GPIO_PIN_11)
// You can do some safe, non-destructive testing on any platform with:
// gcc bcm2835.c -D BCM2835_TEST
// ./a.out
*/
/*#define BCM2835_TEST*/

/* Uncommenting this define compiles alternative I2C code for the version 1 RPi
// The P1 header I2C pins are connected to SDA0 and SCL0 on V1.
// By default I2C code is generated for the V2 RPi which has SDA1 and SCL1 connected.
*/
/* #define I2C_V1*/

/* Physical address and size of the peripherals block
// May be overridden on RPi2
*/
uint32_t* bcm2835_peripherals_base = (uint32_t*) BCM2835_PERI_BASE;
uint32_t bcm2835_peripherals_size = BCM2835_PERI_SIZE;

/* Virtual memory address of the mapped peripherals block 
 */
uint32_t* bcm2835_peripherals = (uint32_t*) MAP_FAILED;

/* And the register bases within the peripherals block
 */
volatile uint32_t* bcm2835_gpio = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_pwm = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_clk = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_pads = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_spi0 = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_bsc0 = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_bsc1 = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_st = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_aux = (uint32_t*) MAP_FAILED;
volatile uint32_t* bcm2835_spi1 = (uint32_t*) MAP_FAILED;

/* This variable allows us to test on hardware other than RPi.
// It prevents access to the kernel memory, and does not do any peripheral access
// Instead it prints out what it _would_ do if debug were 0
 */
static uint8_t debug = 0;

/* RPI 4 has different pullup registers - we need to know if we have that type */

static uint8_t pud_type_rpi4 = 0;

/* RPI 4 has different pullup operation - make backwards compat */

static uint8_t pud_compat_setting = BCM2835_GPIO_PUD_OFF;

/* I2C The time needed to transmit one byte. In microseconds.
 */
static int i2c_byte_wait_us = 0;

// Time for millis()
static unsigned long long epoch;

/* SPI bit order. BCM2835 SPI0 only supports MSBFIRST, so we instead 
 * have a software based bit reversal, based on a contribution by Damiano Benedetti
 */
static uint8_t bcm2835_spi_bit_order = BCM2835_SPI_BIT_ORDER_MSBFIRST;
static uint8_t bcm2835_byte_reverse_table[] = {0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70,
                                               0xf0, 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8,
                                               0x78, 0xf8, 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34,
                                               0xb4, 0x74, 0xf4, 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc,
                                               0x3c, 0xbc, 0x7c, 0xfc, 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 0x12, 0x92, 0x52,
                                               0xd2, 0x32, 0xb2, 0x72, 0xf2, 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a,
                                               0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16,
                                               0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
                                               0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61,
                                               0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9,
                                               0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, 0x05, 0x85, 0x45, 0xc5, 0x25,
                                               0xa5, 0x65, 0xe5, 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 0x0d, 0x8d, 0x4d, 0xcd,
                                               0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, 0x03, 0x83, 0x43,
                                               0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, 0x0b, 0x8b,
                                               0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 0x07,
                                               0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
                                               0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f,
                                               0xff};

static uint8_t bcm2835_correct_order(uint8_t b)
{
    if (bcm2835_spi_bit_order == BCM2835_SPI_BIT_ORDER_LSBFIRST) {
        return bcm2835_byte_reverse_table[b];
    } else {
        return b;
    }
}

/*
// Low level register access functions
*/

/* Function to return the pointers to the hardware register bases */
uint32_t* bcm2835_regbase(uint8_t regbase)
{
    switch (regbase) {
        case BCM2835_REGBASE_ST:
            return (uint32_t*) bcm2835_st;
        case BCM2835_REGBASE_GPIO:
            return (uint32_t*) bcm2835_gpio;
        case BCM2835_REGBASE_PWM:
            return (uint32_t*) bcm2835_pwm;
        case BCM2835_REGBASE_CLK:
            return (uint32_t*) bcm2835_clk;
        case BCM2835_REGBASE_PADS:
            return (uint32_t*) bcm2835_pads;
        case BCM2835_REGBASE_SPI0:
            return (uint32_t*) bcm2835_spi0;
        case BCM2835_REGBASE_BSC0:
            return (uint32_t*) bcm2835_bsc0;
        case BCM2835_REGBASE_BSC1:
            return (uint32_t*) bcm2835_st;
        case BCM2835_REGBASE_AUX:
            return (uint32_t*) bcm2835_aux;
        case BCM2835_REGBASE_SPI1:
            return (uint32_t*) bcm2835_spi1;

    }
    return (uint32_t*) MAP_FAILED;
}

void bcm2835_set_debug(uint8_t d)
{
    debug = d;
}

unsigned int bcm2835_version(void)
{
    return BCM2835_VERSION;
}

/* Read with memory barriers from peripheral
 *
 */
uint32_t bcm2835_peri_read(volatile uint32_t* paddr)
{
    uint32_t ret;
    if (debug) {
        printf("bcm2835_peri_read  paddr %p\n", (void*) paddr);
        return 0;
    } else {
        __sync_synchronize();
        ret = *paddr;
        __sync_synchronize();
        return ret;
    }
}

/* read from peripheral without the read barrier
 * This can only be used if more reads to THE SAME peripheral
 * will follow.  The sequence must terminate with memory barrier
 * before any read or write to another peripheral can occur.
 * The MB can be explicit, or one of the barrier read/write calls.
 */
uint32_t bcm2835_peri_read_nb(volatile uint32_t* paddr)
{
    if (debug) {
        printf("bcm2835_peri_read_nb  paddr %p\n", paddr);
        return 0;
    } else {
        return *paddr;
    }
}

/* Write with memory barriers to peripheral
 */

void bcm2835_peri_write(volatile uint32_t* paddr, uint32_t value)
{
    if (debug) {
        printf("bcm2835_peri_write paddr %p, value %08X\n", paddr, value);
    } else {
        __sync_synchronize();
        *paddr = value;
        __sync_synchronize();
    }
}

/* write to peripheral without the write barrier */
void bcm2835_peri_write_nb(volatile uint32_t* paddr, uint32_t value)
{
    if (debug) {
        printf("bcm2835_peri_write_nb paddr %p, value %08X\n", paddr, value);
    } else {
        *paddr = value;
    }
}

/* Set/clear only the bits in value covered by the mask
 * This is not atomic - can be interrupted.
 */
void bcm2835_peri_set_bits(volatile uint32_t* paddr, uint32_t value, uint32_t mask)
{
    uint32_t v = bcm2835_peri_read(paddr);
    v = (v & ~mask) | (value & mask);
    bcm2835_peri_write(paddr, v);
}

/*
// Low level convenience functions
*/

/* Function select
// pin is a BCM2835 GPIO pin number NOT RPi pin number
//      There are 6 control registers, each control the functions of a block
//      of 10 pins.
//      Each control register has 10 sets of 3 bits per GPIO pin:
//
//      000 = GPIO Pin X is an input
//      001 = GPIO Pin X is an output
//      100 = GPIO Pin X takes alternate function 0
//      101 = GPIO Pin X takes alternate function 1
//      110 = GPIO Pin X takes alternate function 2
//      111 = GPIO Pin X takes alternate function 3
//      011 = GPIO Pin X takes alternate function 4
//      010 = GPIO Pin X takes alternate function 5
//
// So the 3 bits for port X are:
//      X / 10 + ((X % 10) * 3)
*/
void bcm2835_gpio_fsel(uint8_t pin, uint8_t mode)
{
    /* Function selects are 10 pins per 32 bit word, 3 bits per pin */
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFSEL0 / 4 + (pin / 10);
    uint8_t shift = (pin % 10) * 3;
    uint32_t mask = BCM2835_GPIO_FSEL_MASK << shift;
    uint32_t value = mode << shift;
    bcm2835_peri_set_bits(paddr, value, mask);
}

/* Set output pin */
void bcm2835_gpio_set(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPSET0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    bcm2835_peri_write(paddr, 1 << shift);
}

/* Clear output pin */
void bcm2835_gpio_clr(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPCLR0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    bcm2835_peri_write(paddr, 1 << shift);
}

/* Set all output pins in the mask */
void bcm2835_gpio_set_multi(uint32_t mask)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPSET0 / 4;
    bcm2835_peri_write(paddr, mask);
}

/* Clear all output pins in the mask */
void bcm2835_gpio_clr_multi(uint32_t mask)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPCLR0 / 4;
    bcm2835_peri_write(paddr, mask);
}

/* Read input pin */
uint8_t bcm2835_gpio_lev(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEV0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = bcm2835_peri_read(paddr);
    return (value & (1 << shift)) ? HIGH : LOW;
}

/* See if an event detection bit is set
// Sigh cant support interrupts yet
*/
uint8_t bcm2835_gpio_eds(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = bcm2835_peri_read(paddr);
    return (value & (1 << shift)) ? HIGH : LOW;
}

uint32_t bcm2835_gpio_eds_multi(uint32_t mask)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0 / 4;
    uint32_t value = bcm2835_peri_read(paddr);
    return (value & mask);
}

/* Write a 1 to clear the bit in EDS */
void bcm2835_gpio_set_eds(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_write(paddr, value);
}

void bcm2835_gpio_set_eds_multi(uint32_t mask)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0 / 4;
    bcm2835_peri_write(paddr, mask);
}

/* Rising edge detect enable */
void bcm2835_gpio_ren(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPREN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_ren(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPREN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* Falling edge detect enable */
void bcm2835_gpio_fen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_fen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* High detect enable */
void bcm2835_gpio_hen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPHEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_hen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPHEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* Low detect enable */
void bcm2835_gpio_len(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_len(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* Async rising edge detect enable */
void bcm2835_gpio_aren(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAREN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_aren(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAREN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* Async falling edge detect enable */
void bcm2835_gpio_afen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAFEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, value, value);
}

void bcm2835_gpio_clr_afen(uint8_t pin)
{
    volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAFEN0 / 4 + pin / 32;
    uint8_t shift = pin % 32;
    uint32_t value = 1 << shift;
    bcm2835_peri_set_bits(paddr, 0, value);
}

/* Set pullup/down */
void bcm2835_gpio_pud(uint8_t pud)
{
    if (pud_type_rpi4) {
        pud_compat_setting = pud;
    } else {
        volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUD / 4;
        bcm2835_peri_write(paddr, pud);
    }
}

/* Pullup/down clock
// Clocks the value of pud into the GPIO pin
*/
void bcm2835_gpio_pudclk(uint8_t pin, uint8_t on)
{
    if (pud_type_rpi4) {
        if (on) {
            bcm2835_gpio_set_pud(pin, pud_compat_setting);
        }
    } else {
        volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUDCLK0 / 4 + pin / 32;
        uint8_t shift = pin % 32;
        bcm2835_peri_write(paddr, (on ? 1 : 0) << shift);
    }
}

/* Read GPIO pad behaviour for groups of GPIOs */
uint32_t bcm2835_gpio_pad(uint8_t group)
{
    if (bcm2835_pads == MAP_FAILED) {
        return 0;
    }

    volatile uint32_t* paddr = bcm2835_pads + BCM2835_PADS_GPIO_0_27 / 4 + group;
    return bcm2835_peri_read(paddr);
}

/* Set GPIO pad behaviour for groups of GPIOs
// powerup value for all pads is
// BCM2835_PAD_SLEW_RATE_UNLIMITED | BCM2835_PAD_HYSTERESIS_ENABLED | BCM2835_PAD_DRIVE_8mA
*/
void bcm2835_gpio_set_pad(uint8_t group, uint32_t control)
{
    if (bcm2835_pads == MAP_FAILED) {
        return;
    }

    volatile uint32_t* paddr = bcm2835_pads + BCM2835_PADS_GPIO_0_27 / 4 + group;
    bcm2835_peri_write(paddr, control | BCM2835_PAD_PASSWRD);
}

/* Some convenient arduino-like functions
// milliseconds
*/
void bcm2835_delay(unsigned int millis)
{
    struct timespec sleeper;

    sleeper.tv_sec = (time_t)(millis / 1000);
    sleeper.tv_nsec = (long) (millis % 1000) * 1000000;
    nanosleep(&sleeper, NULL);
}

/* microseconds */
void bcm2835_delayMicroseconds(uint64_t micros)
{
    struct timespec t1;
    uint64_t start;

    if (debug) {
        /* Cant access sytem timers in debug mode */
        printf("bcm2835_delayMicroseconds %lld\n", (long long int) micros);
        return;
    }

    /* Calling nanosleep() takes at least 100-200 us, so use it for
    // long waits and use a busy wait on the System Timer for the rest.
    */
    start = bcm2835_st_read();

    /* Not allowed to access timer registers (result is not as precise)*/
    if (start == 0) {
        t1.tv_sec = 0;
        t1.tv_nsec = 1000 * (long) (micros);
        nanosleep(&t1, NULL);
        return;
    }

    if (micros > 450) {
        t1.tv_sec = 0;
        t1.tv_nsec = 1000 * (long) (micros - 200);
        nanosleep(&t1, NULL);
    }

    bcm2835_st_delay(start, micros);
}

// This function is added in order to simulate arduino millis() function
unsigned int bcm2835_millis(void)
{
    struct timeval now;
    unsigned long long ms;

    gettimeofday(&now, NULL);

    ms = (now.tv_sec * 1000000 + now.tv_usec) / 1000;

    return ((uint32_t)(ms - epoch));
}

/*
// Higher level convenience functions
*/

/* Set the state of an output */
void bcm2835_gpio_write(uint8_t pin, uint8_t on)
{
    if (on) {
        bcm2835_gpio_set(pin);
    } else {
        bcm2835_gpio_clr(pin);
    }
}

/* Set the state of a all 32 outputs in the mask to on or off */
void bcm2835_gpio_write_multi(uint32_t mask, uint8_t on)
{
    if (on) {
        bcm2835_gpio_set_multi(mask);
    } else {
        bcm2835_gpio_clr_multi(mask);
    }
}

/* Set the state of a all 32 outputs in the mask to the values in value */
void bcm2835_gpio_write_mask(uint32_t value, uint32_t mask)
{
    bcm2835_gpio_set_multi(value & mask);
    bcm2835_gpio_clr_multi((~value) & mask);
}

/* Set the pullup/down resistor for a pin
//
// The GPIO Pull-up/down Clock Registers control the actuation of internal pull-downs on
// the respective GPIO pins. These registers must be used in conjunction with the GPPUD
// register to effect GPIO Pull-up/down changes. The following sequence of events is
// required:
// 1. Write to GPPUD to set the required control signal (i.e. Pull-up or Pull-Down or neither
// to remove the current Pull-up/down)
// 2. Wait 150 cycles ? this provides the required set-up time for the control signal
// 3. Write to GPPUDCLK0/1 to clock the control signal into the GPIO pads you wish to
// modify ? NOTE only the pads which receive a clock will be modified, all others will
// retain their previous state.
// 4. Wait 150 cycles ? this provides the required hold time for the control signal
// 5. Write to GPPUD to remove the control signal
// 6. Write to GPPUDCLK0/1 to remove the clock
//
// RPi has P1-03 and P1-05 with 1k8 pullup resistor
//
// RPI 4 uses a different PUD method - no clock

*/
void bcm2835_gpio_set_pud(uint8_t pin, uint8_t pud)
{
    if (pud_type_rpi4) {
        int shiftbits = (pin & 0xf) << 1;
        uint32_t bits;
        uint32_t pull;

        switch (pud) {
            case BCM2835_GPIO_PUD_OFF:
                pull = 0;
                break;
            case BCM2835_GPIO_PUD_UP:
                pull = 1;
                break;
            case BCM2835_GPIO_PUD_DOWN:
                pull = 2;
                break;
            default:
                return;
        }

        volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUPPDN0 / 4 + (pin >> 4);

        bits = bcm2835_peri_read_nb(paddr);
        bits &= ~(3 << shiftbits);
        bits |= (pull << shiftbits);

        bcm2835_peri_write_nb(paddr, bits);

    } else {
        bcm2835_gpio_pud(pud);
        delayMicroseconds(10);
        bcm2835_gpio_pudclk(pin, 1);
        delayMicroseconds(10);
        bcm2835_gpio_pud(BCM2835_GPIO_PUD_OFF);
        bcm2835_gpio_pudclk(pin, 0);
    }

}

uint8_t bcm2835_gpio_get_pud(uint8_t pin)
{
    uint8_t ret = BCM2835_GPIO_PUD_ERROR;

    if (pud_type_rpi4) {
        uint32_t bits;
        volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUPPDN0 / 4 + (pin >> 4);
        bits = (bcm2835_peri_read_nb(paddr) >> ((pin & 0xf) << 1)) & 0x3;

        switch (bits) {
            case 0:
                ret = BCM2835_GPIO_PUD_OFF;
                break;
            case 1:
                ret = BCM2835_GPIO_PUD_UP;
                break;
            case 2:
                ret = BCM2835_GPIO_PUD_DOWN;
                break;
            default:
                ret = BCM2835_GPIO_PUD_ERROR;
        }
    }

    return ret;
}

int bcm2835_spi_begin(void)
{
    volatile uint32_t* paddr;

    if (bcm2835_spi0 == MAP_FAILED) {
        return 0;
    } /* bcm2835_init() failed, or not root */

    /* Set the SPI0 pins to the Alt 0 function to enable SPI0 access on them */
    bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_ALT0); /* CE1 */
    bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_ALT0); /* CE0 */
    bcm2835_gpio_fsel(RPI_GPIO_P1_21, BCM2835_GPIO_FSEL_ALT0); /* MISO */
    bcm2835_gpio_fsel(RPI_GPIO_P1_19, BCM2835_GPIO_FSEL_ALT0); /* MOSI */
    bcm2835_gpio_fsel(RPI_GPIO_P1_23, BCM2835_GPIO_FSEL_ALT0); /* CLK */

    /* Set the SPI CS register to the some sensible defaults */
    paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    bcm2835_peri_write(paddr, 0); /* All 0s */

    /* Clear TX and RX fifos */
    bcm2835_peri_write_nb(paddr, BCM2835_SPI0_CS_CLEAR);

    return 1; // OK
}

void bcm2835_spi_end(void)
{
    /* Set all the SPI0 pins back to input */
    bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_INPT); /* CE1 */
    bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_INPT); /* CE0 */
    bcm2835_gpio_fsel(RPI_GPIO_P1_21, BCM2835_GPIO_FSEL_INPT); /* MISO */
    bcm2835_gpio_fsel(RPI_GPIO_P1_19, BCM2835_GPIO_FSEL_INPT); /* MOSI */
    bcm2835_gpio_fsel(RPI_GPIO_P1_23, BCM2835_GPIO_FSEL_INPT); /* CLK */
}

void bcm2835_spi_setBitOrder(uint8_t order)
{
    bcm2835_spi_bit_order = order;
}

/* defaults to 0, which means a divider of 65536.
// The divisor must be a power of 2. Odd numbers
// rounded down. The maximum SPI clock rate is
// of the APB clock
*/
void bcm2835_spi_setClockDivider(uint16_t divider)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CLK / 4;
    bcm2835_peri_write(paddr, divider);
}

void bcm2835_spi_set_speed_hz(uint32_t speed_hz)
{
    uint16_t divider = (uint16_t)((uint32_t) BCM2835_CORE_CLK_HZ / speed_hz);
    divider &= 0xFFFE;
    bcm2835_spi_setClockDivider(divider);
}

void bcm2835_spi_setDataMode(uint8_t mode)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    /* Mask in the CPO and CPHA bits of CS */
    bcm2835_peri_set_bits(paddr, mode << 2, BCM2835_SPI0_CS_CPOL | BCM2835_SPI0_CS_CPHA);
}

/* Writes (and reads) a single byte to SPI */
uint8_t bcm2835_spi_transfer(uint8_t value)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO / 4;
    uint32_t ret;

    /* This is Polled transfer as per section 10.6.1
    // BUG ALERT: what happens if we get interupted in this section, and someone else
    // accesses a different peripheral? 
    // Clear TX and RX fifos
    */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);

    /* Set TA = 1 */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);

    /* Maybe wait for TXD */
    while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD)) {
    }

    /* Write to FIFO, no barrier */
    bcm2835_peri_write_nb(fifo, bcm2835_correct_order(value));

    /* Wait for DONE to be set */
    while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE)) {
    }

    /* Read any byte that was sent back by the slave while we sere sending to it */
    ret = bcm2835_correct_order(bcm2835_peri_read_nb(fifo));

    /* Set TA = 0, and also set the barrier */
    bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);

    return ret;
}

/* Writes (and reads) an number of bytes to SPI */
void bcm2835_spi_transfernb(char* tbuf, char* rbuf, uint32_t len)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO / 4;
    uint32_t TXCnt = 0;
    uint32_t RXCnt = 0;

    /* This is Polled transfer as per section 10.6.1
    // BUG ALERT: what happens if we get interupted in this section, and someone else
    // accesses a different peripheral? 
    */

    /* Clear TX and RX fifos */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);

    /* Set TA = 1 */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);

    /* Use the FIFO's to reduce the interbyte times */
    while ((TXCnt < len) || (RXCnt < len)) {
        /* TX fifo not full, so add some more bytes */
        while (((bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD)) && (TXCnt < len)) {
            bcm2835_peri_write_nb(fifo, bcm2835_correct_order(tbuf[TXCnt]));
            TXCnt++;
        }
        /* Rx fifo not empty, so get the next received bytes */
        while (((bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD)) && (RXCnt < len)) {
            rbuf[RXCnt] = bcm2835_correct_order(bcm2835_peri_read_nb(fifo));
            RXCnt++;
        }
    }
    /* Wait for DONE to be set */
    while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE)) {
    }

    /* Set TA = 0, and also set the barrier */
    bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
}

/* Writes an number of bytes to SPI */
void bcm2835_spi_writenb(const char* tbuf, uint32_t len)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO / 4;
    uint32_t i;

    /* This is Polled transfer as per section 10.6.1
    // BUG ALERT: what happens if we get interupted in this section, and someone else
    // accesses a different peripheral?
    // Answer: an ISR is required to issue the required memory barriers.
    */

    /* Clear TX and RX fifos */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);

    /* Set TA = 1 */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);

    for (i = 0; i < len; i++) {
        /* Maybe wait for TXD */
        while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD)) {
        }

        /* Write to FIFO, no barrier */
        bcm2835_peri_write_nb(fifo, bcm2835_correct_order(tbuf[i]));

        /* Read from FIFO to prevent stalling */
        while (bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD) {
            (void) bcm2835_peri_read_nb(fifo);
        }
    }

    /* Wait for DONE to be set */
    while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE)) {
        while (bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD) {
            (void) bcm2835_peri_read_nb(fifo);
        }
    };

    /* Set TA = 0, and also set the barrier */
    bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
}

/* Writes (and reads) an number of bytes to SPI
// Read bytes are copied over onto the transmit buffer
*/
void bcm2835_spi_transfern(char* buf, uint32_t len)
{
    bcm2835_spi_transfernb(buf, buf, len);
}

void bcm2835_spi_chipSelect(uint8_t cs)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    /* Mask in the CS bits of CS */
    bcm2835_peri_set_bits(paddr, cs, BCM2835_SPI0_CS_CS);
}

void bcm2835_spi_setChipSelectPolarity(uint8_t cs, uint8_t active)
{
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    uint8_t shift = 21 + cs;
    /* Mask in the appropriate CSPOLn bit */
    bcm2835_peri_set_bits(paddr, active << shift, 1 << shift);
}

void bcm2835_spi_write(uint16_t data)
{
    #if 0
    char buf[2];

    buf[0] = data >> 8;
    buf[1] = data & 0xFF;

    bcm2835_spi_transfern(buf, 2);
    #else
    volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS / 4;
    volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO / 4;

    /* Clear TX and RX fifos */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);

    /* Set TA = 1 */
    bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);

    /* Maybe wait for TXD */
    while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD)) {
    }

    /* Write to FIFO */
    bcm2835_peri_write_nb(fifo, (uint32_t) data >> 8);
    bcm2835_peri_write_nb(fifo, data & 0xFF);


    /* Wait for DONE to be set */
    while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE)) {
    }

    /* Set TA = 0, and also set the barrier */
    bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
    #endif
}

int bcm2835_aux_spi_begin(void)
{
    volatile uint32_t* enable = bcm2835_aux + BCM2835_AUX_ENABLE / 4;
    volatile uint32_t* cntl0 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL0 / 4;
    volatile uint32_t* cntl1 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL1 / 4;

    if (bcm2835_spi1 == MAP_FAILED) {
        return 0;
    } /* bcm2835_init() failed, or not root */

    /* Set the SPI pins to the Alt 4 function to enable SPI1 access on them */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_36, BCM2835_GPIO_FSEL_ALT4);    /* SPI1_CE2_N */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_35, BCM2835_GPIO_FSEL_ALT4);    /* SPI1_MISO */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_38, BCM2835_GPIO_FSEL_ALT4);    /* SPI1_MOSI */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_40, BCM2835_GPIO_FSEL_ALT4);    /* SPI1_SCLK */

    bcm2835_aux_spi_setClockDivider(bcm2835_aux_spi_CalcClockDivider(1000000));    // Default 1MHz SPI

    bcm2835_peri_write(enable, BCM2835_AUX_ENABLE_SPI0);
    bcm2835_peri_write(cntl1, 0);
    bcm2835_peri_write(cntl0, BCM2835_AUX_SPI_CNTL0_CLEARFIFO);

    return 1; /* OK */
}

void bcm2835_aux_spi_end(void)
{
    /* Set all the SPI1 pins back to input */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_36, BCM2835_GPIO_FSEL_INPT);    /* SPI1_CE2_N */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_35, BCM2835_GPIO_FSEL_INPT);    /* SPI1_MISO */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_38, BCM2835_GPIO_FSEL_INPT);    /* SPI1_MOSI */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_40, BCM2835_GPIO_FSEL_INPT);    /* SPI1_SCLK */
}

#define DIV_ROUND_UP(n, d)    (((n) + (d) - 1) / (d))

uint16_t bcm2835_aux_spi_CalcClockDivider(uint32_t speed_hz)
{
    uint16_t divider;

    if (speed_hz < (uint32_t) BCM2835_AUX_SPI_CLOCK_MIN) {
        speed_hz = (uint32_t) BCM2835_AUX_SPI_CLOCK_MIN;
    } else if (speed_hz > (uint32_t) BCM2835_AUX_SPI_CLOCK_MAX) {
        speed_hz = (uint32_t) BCM2835_AUX_SPI_CLOCK_MAX;
    }

    divider = (uint16_t)DIV_ROUND_UP(BCM2835_CORE_CLK_HZ, 2 * speed_hz) - 1;

    if (divider > (uint16_t) BCM2835_AUX_SPI_CNTL0_SPEED_MAX) {
        return (uint16_t) BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
    }

    return divider;
}

static uint32_t spi1_speed;

void bcm2835_aux_spi_setClockDivider(uint16_t divider)
{
    spi1_speed = (uint32_t) divider;
}

void bcm2835_aux_spi_write(uint16_t data)
{
    volatile uint32_t* cntl0 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL0 / 4;
    volatile uint32_t* cntl1 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL1 / 4;
    volatile uint32_t* stat = bcm2835_spi1 + BCM2835_AUX_SPI_STAT / 4;
    volatile uint32_t* io = bcm2835_spi1 + BCM2835_AUX_SPI_IO / 4;

    uint32_t _cntl0 = (spi1_speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT);
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_CS2_N;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_ENABLE;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
    _cntl0 |= 16; // Shift length

    bcm2835_peri_write(cntl0, _cntl0);
    bcm2835_peri_write(cntl1, BCM2835_AUX_SPI_CNTL1_MSBF_IN);

    while (bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_TX_FULL) {
    }

    bcm2835_peri_write(io, (uint32_t) data << 16);
}

void bcm2835_aux_spi_writenb(const char* tbuf, uint32_t len)
{
    volatile uint32_t* cntl0 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL0 / 4;
    volatile uint32_t* cntl1 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL1 / 4;
    volatile uint32_t* stat = bcm2835_spi1 + BCM2835_AUX_SPI_STAT / 4;
    volatile uint32_t* txhold = bcm2835_spi1 + BCM2835_AUX_SPI_TXHOLD / 4;
    volatile uint32_t* io = bcm2835_spi1 + BCM2835_AUX_SPI_IO / 4;

    char* tx = (char*) tbuf;
    uint32_t tx_len = len;
    uint32_t count;
    uint32_t data;
    uint32_t i;
    uint8_t byte;

    uint32_t _cntl0 = (spi1_speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT);
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_CS2_N;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_ENABLE;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_VAR_WIDTH;

    bcm2835_peri_write(cntl0, _cntl0);
    bcm2835_peri_write(cntl1, BCM2835_AUX_SPI_CNTL1_MSBF_IN);

    while (tx_len > 0) {

        while (bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_TX_FULL) {
        }

        count = MIN(tx_len, 3);
        data = 0;

        for (i = 0; i < count; i++) {
            byte = (tx != NULL) ? (uint8_t) * tx++ : (uint8_t) 0;
            data |= byte << (8 * (2 - i));
        }

        data |= (count * 8) << 24;
        tx_len -= count;

        if (tx_len != 0) {
            bcm2835_peri_write(txhold, data);
        } else {
            bcm2835_peri_write(io, data);
        }

        while (bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_BUSY) {
        }

        (void) bcm2835_peri_read(io);
    }
}

void bcm2835_aux_spi_transfernb(const char* tbuf, char* rbuf, uint32_t len)
{
    volatile uint32_t* cntl0 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL0 / 4;
    volatile uint32_t* cntl1 = bcm2835_spi1 + BCM2835_AUX_SPI_CNTL1 / 4;
    volatile uint32_t* stat = bcm2835_spi1 + BCM2835_AUX_SPI_STAT / 4;
    volatile uint32_t* txhold = bcm2835_spi1 + BCM2835_AUX_SPI_TXHOLD / 4;
    volatile uint32_t* io = bcm2835_spi1 + BCM2835_AUX_SPI_IO / 4;

    char* tx = (char*) tbuf;
    char* rx = (char*) rbuf;
    uint32_t tx_len = len;
    uint32_t rx_len = len;
    uint32_t count;
    uint32_t data;
    uint32_t i;
    uint8_t byte;

    uint32_t _cntl0 = (spi1_speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT);
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_CS2_N;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_ENABLE;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
    _cntl0 |= BCM2835_AUX_SPI_CNTL0_VAR_WIDTH;

    bcm2835_peri_write(cntl0, _cntl0);
    bcm2835_peri_write(cntl1, BCM2835_AUX_SPI_CNTL1_MSBF_IN);

    while ((tx_len > 0) || (rx_len > 0)) {

        while (!(bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_TX_FULL) && (tx_len > 0)) {
            count = MIN(tx_len, 3);
            data = 0;

            for (i = 0; i < count; i++) {
                byte = (tx != NULL) ? (uint8_t) * tx++ : (uint8_t) 0;
                data |= byte << (8 * (2 - i));
            }

            data |= (count * 8) << 24;
            tx_len -= count;

            if (tx_len != 0) {
                bcm2835_peri_write(txhold, data);
            } else {
                bcm2835_peri_write(io, data);
            }

        }

        while (!(bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_RX_EMPTY) && (rx_len > 0)) {
            count = MIN(rx_len, 3);
            data = bcm2835_peri_read(io);

            if (rbuf != NULL) {
                switch (count) {
                    case 3:
                        *rx++ = (char) ((data >> 16) & 0xFF);
                        /*@fallthrough@*/
                        /* no break */
                    case 2:
                        *rx++ = (char) ((data >> 8) & 0xFF);
                        /*@fallthrough@*/
                        /* no break */
                    case 1:
                        *rx++ = (char) ((data >> 0) & 0xFF);
                }
            }

            rx_len -= count;
        }

        while (!(bcm2835_peri_read(stat) & BCM2835_AUX_SPI_STAT_BUSY) && (rx_len > 0)) {
            count = MIN(rx_len, 3);
            data = bcm2835_peri_read(io);

            if (rbuf != NULL) {
                switch (count) {
                    case 3:
                        *rx++ = (char) ((data >> 16) & 0xFF);
                        /*@fallthrough@*/
                        /* no break */
                    case 2:
                        *rx++ = (char) ((data >> 8) & 0xFF);
                        /*@fallthrough@*/
                        /* no break */
                    case 1:
                        *rx++ = (char) ((data >> 0) & 0xFF);
                }
            }

            rx_len -= count;
        }
    }
}

void bcm2835_aux_spi_transfern(char* buf, uint32_t len)
{
    bcm2835_aux_spi_transfernb(buf, buf, len);
}

int bcm2835_i2c_begin(void)
{
    uint16_t cdiv;

    if (bcm2835_bsc0 == MAP_FAILED || bcm2835_bsc1 == MAP_FAILED) {
        return 0;
    } /* bcm2835_init() failed, or not root */

    #ifdef I2C_V1
    volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_DIV/4;
    /* Set the I2C/BSC0 pins to the Alt 0 function to enable I2C access on them */
    bcm2835_gpio_fsel(RPI_GPIO_P1_03, BCM2835_GPIO_FSEL_ALT0); /* SDA */
    bcm2835_gpio_fsel(RPI_GPIO_P1_05, BCM2835_GPIO_FSEL_ALT0); /* SCL */
    #else
    volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_DIV / 4;
    /* Set the I2C/BSC1 pins to the Alt 0 function to enable I2C access on them */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_03, BCM2835_GPIO_FSEL_ALT0); /* SDA */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_05, BCM2835_GPIO_FSEL_ALT0); /* SCL */
    #endif

    /* Read the clock divider register */
    cdiv = bcm2835_peri_read(paddr);
    /* Calculate time for transmitting one byte
    // 1000000 = micros seconds in a second
    // 9 = Clocks per byte : 8 bits + ACK
    */
    i2c_byte_wait_us = ((float) cdiv / BCM2835_CORE_CLK_HZ) * 1000000 * 9;

    return 1;
}

void bcm2835_i2c_end(void)
{
    #ifdef I2C_V1
    /* Set all the I2C/BSC0 pins back to input */
    bcm2835_gpio_fsel(RPI_GPIO_P1_03, BCM2835_GPIO_FSEL_INPT); /* SDA */
    bcm2835_gpio_fsel(RPI_GPIO_P1_05, BCM2835_GPIO_FSEL_INPT); /* SCL */
    #else
    /* Set all the I2C/BSC1 pins back to input */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_03, BCM2835_GPIO_FSEL_INPT); /* SDA */
    bcm2835_gpio_fsel(RPI_V2_GPIO_P1_05, BCM2835_GPIO_FSEL_INPT); /* SCL */
    #endif
}

void bcm2835_i2c_setSlaveAddress(uint8_t addr)
{
    /* Set I2C Device Address */
    #ifdef I2C_V1
    volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_A/4;
    #else
    volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_A / 4;
    #endif
    bcm2835_peri_write(paddr, addr);
}

/* defaults to 0x5dc, should result in a 166.666 kHz I2C clock frequency.
// The divisor must be a power of 2. Odd numbers
// rounded down.
*/
void bcm2835_i2c_setClockDivider(uint16_t divider)
{
    #ifdef I2C_V1
    volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_DIV/4;
    #else
    volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_DIV / 4;
    #endif
    bcm2835_peri_write(paddr, divider);
    /* Calculate time for transmitting one byte
    // 1000000 = micros seconds in a second
    // 9 = Clocks per byte : 8 bits + ACK
    */
    i2c_byte_wait_us = ((float) divider / BCM2835_CORE_CLK_HZ) * 1000000 * 9;
}

/* set I2C clock divider by means of a baudrate number */
void bcm2835_i2c_set_baudrate(uint32_t baudrate)
{
    uint32_t divider;
    /* use 0xFFFE mask to limit a max value and round down any odd number */
    divider = (BCM2835_CORE_CLK_HZ / baudrate) & 0xFFFE;
    bcm2835_i2c_setClockDivider((uint16_t) divider);
}

/* Writes an number of bytes to I2C */
uint8_t bcm2835_i2c_write(const char* buf, uint32_t len)
{
    #ifdef I2C_V1
    volatile uint32_t* dlen    = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
    volatile uint32_t* fifo    = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
    volatile uint32_t* status  = bcm2835_bsc0 + BCM2835_BSC_S/4;
    volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
    #else
    volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN / 4;
    volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO / 4;
    volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S / 4;
    volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C / 4;
    #endif

    uint32_t remaining = len;
    uint32_t i = 0;
    uint8_t reason = BCM2835_I2C_REASON_OK;

    /* Clear FIFO */
    bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1, BCM2835_BSC_C_CLEAR_1);
    /* Clear Status */
    bcm2835_peri_write(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
    /* Set Data Length */
    bcm2835_peri_write(dlen, len);
    /* pre populate FIFO with max buffer */
    while (remaining && (i < BCM2835_BSC_FIFO_SIZE)) {
        bcm2835_peri_write_nb(fifo, buf[i]);
        i++;
        remaining--;
    }

    /* Enable device and start transfer */
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST);

    /* Transfer is over when BCM2835_BSC_S_DONE */
    while (!(bcm2835_peri_read(status) & BCM2835_BSC_S_DONE)) {
        while (remaining && (bcm2835_peri_read(status) & BCM2835_BSC_S_TXD)) {
            /* Write to FIFO */
            bcm2835_peri_write(fifo, buf[i]);
            i++;
            remaining--;
        }
    }

    /* Received a NACK */
    if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR) {
        reason = BCM2835_I2C_REASON_ERROR_NACK;
    }

        /* Received Clock Stretch Timeout */
    else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT) {
        reason = BCM2835_I2C_REASON_ERROR_CLKT;
    }

        /* Not all data is sent */
    else if (remaining) {
        reason = BCM2835_I2C_REASON_ERROR_DATA;
    }

    bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE, BCM2835_BSC_S_DONE);

    return reason;
}

/* Read an number of bytes from I2C */
uint8_t bcm2835_i2c_read(char* buf, uint32_t len)
{
    #ifdef I2C_V1
    volatile uint32_t* dlen    = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
    volatile uint32_t* fifo    = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
    volatile uint32_t* status  = bcm2835_bsc0 + BCM2835_BSC_S/4;
    volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
    #else
    volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN / 4;
    volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO / 4;
    volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S / 4;
    volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C / 4;
    #endif

    uint32_t remaining = len;
    uint32_t i = 0;
    uint8_t reason = BCM2835_I2C_REASON_OK;

    /* Clear FIFO */
    bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1, BCM2835_BSC_C_CLEAR_1);
    /* Clear Status */
    bcm2835_peri_write_nb(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
    /* Set Data Length */
    bcm2835_peri_write_nb(dlen, len);
    /* Start read */
    bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST | BCM2835_BSC_C_READ);

    /* wait for transfer to complete */
    while (!(bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE)) {
        /* we must empty the FIFO as it is populated and not use any delay */
        while (remaining && bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD) {
            /* Read from FIFO, no barrier */
            buf[i] = bcm2835_peri_read_nb(fifo);
            i++;
            remaining--;
        }
    }

    /* transfer has finished - grab any remaining stuff in FIFO */
    while (remaining && (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD)) {
        /* Read from FIFO, no barrier */
        buf[i] = bcm2835_peri_read_nb(fifo);
        i++;
        remaining--;
    }

    /* Received a NACK */
    if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR) {
        reason = BCM2835_I2C_REASON_ERROR_NACK;
    }

        /* Received Clock Stretch Timeout */
    else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT) {
        reason = BCM2835_I2C_REASON_ERROR_CLKT;
    }

        /* Not all data is received */
    else if (remaining) {
        reason = BCM2835_I2C_REASON_ERROR_DATA;
    }

    bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE, BCM2835_BSC_S_DONE);

    return reason;
}

/* Read an number of bytes from I2C sending a repeated start after writing
// the required register. Only works if your device supports this mode
*/
uint8_t bcm2835_i2c_read_register_rs(char* regaddr, char* buf, uint32_t len)
{
    #ifdef I2C_V1
    volatile uint32_t* dlen    = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
    volatile uint32_t* fifo    = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
    volatile uint32_t* status  = bcm2835_bsc0 + BCM2835_BSC_S/4;
    volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
    #else
    volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN / 4;
    volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO / 4;
    volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S / 4;
    volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C / 4;
    #endif
    uint32_t remaining = len;
    uint32_t i = 0;
    uint8_t reason = BCM2835_I2C_REASON_OK;

    /* Clear FIFO */
    bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1, BCM2835_BSC_C_CLEAR_1);
    /* Clear Status */
    bcm2835_peri_write(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
    /* Set Data Length */
    bcm2835_peri_write(dlen, 1);
    /* Enable device and start transfer */
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN);
    bcm2835_peri_write(fifo, regaddr[0]);
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST);

    /* poll for transfer has started */
    while (!(bcm2835_peri_read(status) & BCM2835_BSC_S_TA)) {
        /* Linux may cause us to miss entire transfer stage */
        if (bcm2835_peri_read(status) & BCM2835_BSC_S_DONE) {
            break;
        }
    }

    /* Send a repeated start with read bit set in address */
    bcm2835_peri_write(dlen, len);
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST | BCM2835_BSC_C_READ);

    /* Wait for write to complete and first byte back. */
    bcm2835_delayMicroseconds(i2c_byte_wait_us * 3);

    /* wait for transfer to complete */
    while (!(bcm2835_peri_read(status) & BCM2835_BSC_S_DONE)) {
        /* we must empty the FIFO as it is populated and not use any delay */
        while (remaining && bcm2835_peri_read(status) & BCM2835_BSC_S_RXD) {
            /* Read from FIFO */
            buf[i] = bcm2835_peri_read(fifo);
            i++;
            remaining--;
        }
    }

    /* transfer has finished - grab any remaining stuff in FIFO */
    while (remaining && (bcm2835_peri_read(status) & BCM2835_BSC_S_RXD)) {
        /* Read from FIFO */
        buf[i] = bcm2835_peri_read(fifo);
        i++;
        remaining--;
    }

    /* Received a NACK */
    if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR) {
        reason = BCM2835_I2C_REASON_ERROR_NACK;
    }

        /* Received Clock Stretch Timeout */
    else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT) {
        reason = BCM2835_I2C_REASON_ERROR_CLKT;
    }

        /* Not all data is sent */
    else if (remaining) {
        reason = BCM2835_I2C_REASON_ERROR_DATA;
    }

    bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE, BCM2835_BSC_S_DONE);

    return reason;
}

/* Sending an arbitrary number of bytes before issuing a repeated start 
// (with no prior stop) and reading a response. Some devices require this behavior.
*/
uint8_t bcm2835_i2c_write_read_rs(char* cmds, uint32_t cmds_len, char* buf, uint32_t buf_len)
{
    #ifdef I2C_V1
    volatile uint32_t* dlen    = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
    volatile uint32_t* fifo    = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
    volatile uint32_t* status  = bcm2835_bsc0 + BCM2835_BSC_S/4;
    volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
    #else
    volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN / 4;
    volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO / 4;
    volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S / 4;
    volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C / 4;
    #endif

    uint32_t remaining = cmds_len;
    uint32_t i = 0;
    uint8_t reason = BCM2835_I2C_REASON_OK;

    /* Clear FIFO */
    bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1, BCM2835_BSC_C_CLEAR_1);

    /* Clear Status */
    bcm2835_peri_write(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);

    /* Set Data Length */
    bcm2835_peri_write(dlen, cmds_len);

    /* pre populate FIFO with max buffer */
    while (remaining && (i < BCM2835_BSC_FIFO_SIZE)) {
        bcm2835_peri_write_nb(fifo, cmds[i]);
        i++;
        remaining--;
    }

    /* Enable device and start transfer */
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST);

    /* poll for transfer has started (way to do repeated start, from BCM2835 datasheet) */
    while (!(bcm2835_peri_read(status) & BCM2835_BSC_S_TA)) {
        /* Linux may cause us to miss entire transfer stage */
        if (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE) {
            break;
        }
    }

    remaining = buf_len;
    i = 0;

    /* Send a repeated start with read bit set in address */
    bcm2835_peri_write(dlen, buf_len);
    bcm2835_peri_write(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST | BCM2835_BSC_C_READ);

    /* Wait for write to complete and first byte back. */
    bcm2835_delayMicroseconds(i2c_byte_wait_us * (cmds_len + 1));

    /* wait for transfer to complete */
    while (!(bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE)) {
        /* we must empty the FIFO as it is populated and not use any delay */
        while (remaining && bcm2835_peri_read(status) & BCM2835_BSC_S_RXD) {
            /* Read from FIFO, no barrier */
            buf[i] = bcm2835_peri_read_nb(fifo);
            i++;
            remaining--;
        }
    }

    /* transfer has finished - grab any remaining stuff in FIFO */
    while (remaining && (bcm2835_peri_read(status) & BCM2835_BSC_S_RXD)) {
        /* Read from FIFO */
        buf[i] = bcm2835_peri_read(fifo);
        i++;
        remaining--;
    }

    /* Received a NACK */
    if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR) {
        reason = BCM2835_I2C_REASON_ERROR_NACK;
    }

        /* Received Clock Stretch Timeout */
    else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT) {
        reason = BCM2835_I2C_REASON_ERROR_CLKT;
    }

        /* Not all data is sent */
    else if (remaining) {
        reason = BCM2835_I2C_REASON_ERROR_DATA;
    }

    bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE, BCM2835_BSC_S_DONE);

    return reason;
}

/* Read the System Timer Counter (64-bits) */
uint64_t bcm2835_st_read(void)
{
    volatile uint32_t* paddr;
    uint32_t hi, lo;
    uint64_t st;

    if (bcm2835_st == MAP_FAILED) {
        return 0;
    }

    paddr = bcm2835_st + BCM2835_ST_CHI / 4;
    hi = bcm2835_peri_read(paddr);

    paddr = bcm2835_st + BCM2835_ST_CLO / 4;
    lo = bcm2835_peri_read(paddr);

    paddr = bcm2835_st + BCM2835_ST_CHI / 4;
    st = bcm2835_peri_read(paddr);

    /* Test for overflow */
    if (st == hi) {
        st <<= 32;
        st += lo;
    } else {
        st <<= 32;
        paddr = bcm2835_st + BCM2835_ST_CLO / 4;
        st += bcm2835_peri_read(paddr);
    }
    return st;
}

/* Delays for the specified number of microseconds with offset */
void bcm2835_st_delay(uint64_t offset_micros, uint64_t micros)
{
    uint64_t compare = offset_micros + micros;

    while (bcm2835_st_read() < compare) {
    }
}

/* PWM */

void bcm2835_pwm_set_clock(uint32_t divisor)
{
    if (bcm2835_clk == MAP_FAILED || bcm2835_pwm == MAP_FAILED) {
        return;
    } /* bcm2835_init() failed or not root */

    /* From Gerts code */
    divisor &= 0xfff;
    /* Stop PWM clock */
    bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_CNTL, BCM2835_PWM_PASSWRD | 0x01);
    bcm2835_delay(110); /* Prevents clock going slow */
    /* Wait for the clock to be not busy */
    while ((bcm2835_peri_read(bcm2835_clk + BCM2835_PWMCLK_CNTL) & 0x80) != 0) {
        bcm2835_delay(1);
    }
    /* set the clock divider and enable PWM clock */
    bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_DIV, BCM2835_PWM_PASSWRD | (divisor << 12));
    bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_CNTL, BCM2835_PWM_PASSWRD | 0x11); /* Source=osc and enable */
}

void bcm2835_pwm_set_mode(uint8_t channel, uint8_t markspace, uint8_t enabled)
{
    if (bcm2835_clk == MAP_FAILED || bcm2835_pwm == MAP_FAILED) {
        return;
    } /* bcm2835_init() failed or not root */

    uint32_t control = bcm2835_peri_read(bcm2835_pwm + BCM2835_PWM_CONTROL);

    if (channel == 0) {
        if (markspace) {
            control |= BCM2835_PWM0_MS_MODE;
        } else {
            control &= ~BCM2835_PWM0_MS_MODE;
        }
        if (enabled) {
            control |= BCM2835_PWM0_ENABLE;
        } else {
            control &= ~BCM2835_PWM0_ENABLE;
        }
    } else if (channel == 1) {
        if (markspace) {
            control |= BCM2835_PWM1_MS_MODE;
        } else {
            control &= ~BCM2835_PWM1_MS_MODE;
        }
        if (enabled) {
            control |= BCM2835_PWM1_ENABLE;
        } else {
            control &= ~BCM2835_PWM1_ENABLE;
        }
    }

    /* If you use the barrier here, wierd things happen, and the commands dont work */
    bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM_CONTROL, control);
    /*  bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM_CONTROL, BCM2835_PWM0_ENABLE | BCM2835_PWM1_ENABLE | BCM2835_PWM0_MS_MODE | BCM2835_PWM1_MS_MODE); */

}

void bcm2835_pwm_set_range(uint8_t channel, uint32_t range)
{
    if (bcm2835_clk == MAP_FAILED || bcm2835_pwm == MAP_FAILED) {
        return;
    } /* bcm2835_init() failed or not root */

    if (channel == 0) {
        bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM0_RANGE, range);
    } else if (channel == 1) {
        bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM1_RANGE, range);
    }
}

void bcm2835_pwm_set_data(uint8_t channel, uint32_t data)
{
    if (bcm2835_clk == MAP_FAILED || bcm2835_pwm == MAP_FAILED) {
        return;
    } /* bcm2835_init() failed or not root */

    if (channel == 0) {
        bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM0_DATA, data);
    } else if (channel == 1) {
        bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM1_DATA, data);
    }
}

/* Allocate page-aligned memory. */
void* malloc_aligned(size_t size)
{
    void* mem;
    errno = posix_memalign(&mem, BCM2835_PAGE_SIZE, size);
    return (errno ? NULL : mem);
}

/* Map 'size' bytes starting at 'off' in file 'fd' to memory.
// Return mapped address on success, MAP_FAILED otherwise.
// On error print message.
*/
static void* mapmem(const char* msg, size_t size, int fd, off_t off)
{
    void* map = mmap(NULL, size, (PROT_READ | PROT_WRITE), MAP_SHARED, fd, off);
    if (map == MAP_FAILED) {
        fprintf(stderr, "bcm2835_init: %s mmap failed: %s\n", msg, strerror(errno));
    }
    return map;
}

static void unmapmem(void** pmem, size_t size)
{
    if (*pmem == MAP_FAILED) {
        return;
    }
    munmap(*pmem, size);
    *pmem = MAP_FAILED;
}

/* Initialise this library. */
int bcm2835_init(void)
{
    int memfd;
    int ok;
    FILE* fp;

    if (debug) {
        bcm2835_peripherals = (uint32_t*) BCM2835_PERI_BASE;

        bcm2835_pads = bcm2835_peripherals + BCM2835_GPIO_PADS / 4;
        bcm2835_clk = bcm2835_peripherals + BCM2835_CLOCK_BASE / 4;
        bcm2835_gpio = bcm2835_peripherals + BCM2835_GPIO_BASE / 4;
        bcm2835_pwm = bcm2835_peripherals + BCM2835_GPIO_PWM / 4;
        bcm2835_spi0 = bcm2835_peripherals + BCM2835_SPI0_BASE / 4;
        bcm2835_bsc0 = bcm2835_peripherals + BCM2835_BSC0_BASE / 4;
        bcm2835_bsc1 = bcm2835_peripherals + BCM2835_BSC1_BASE / 4;
        bcm2835_st = bcm2835_peripherals + BCM2835_ST_BASE / 4;
        bcm2835_aux = bcm2835_peripherals + BCM2835_AUX_BASE / 4;
        bcm2835_spi1 = bcm2835_peripherals + BCM2835_SPI1_BASE / 4;

        return 1; /* Success */
    }

    /* Figure out the base and size of the peripheral address block
    // using the device-tree. Required for RPi2/3/4, optional for RPi 1
    */
    if ((fp = fopen(BMC2835_RPI2_DT_FILENAME, "rb"))) {
        unsigned char buf[16];
        uint32_t base_address;
        uint32_t peri_size;
        if (fread(buf, 1, sizeof(buf), fp) >= 8) {
            base_address = (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | (buf[7] << 0);

            peri_size = (buf[8] << 24) | (buf[9] << 16) | (buf[10] << 8) | (buf[11] << 0);

            if (!base_address) {
                /* looks like RPI 4 */
                base_address = (buf[8] << 24) | (buf[9] << 16) | (buf[10] << 8) | (buf[11] << 0);

                peri_size = (buf[12] << 24) | (buf[13] << 16) | (buf[14] << 8) | (buf[15] << 0);
            }
            /* check for valid known range formats */
            if ((buf[0] == 0x7e) && (buf[1] == 0x00) && (buf[2] == 0x00) && (buf[3] == 0x00)
                    && ((base_address == BCM2835_PERI_BASE) || (base_address == BCM2835_RPI2_PERI_BASE)
                            || (base_address == BCM2835_RPI4_PERI_BASE))) {
                bcm2835_peripherals_base = (uint32_t*) base_address;
                bcm2835_peripherals_size = peri_size;
                if (base_address == BCM2835_RPI4_PERI_BASE) {
                    pud_type_rpi4 = 1;
                }
            }

        }

        fclose(fp);
    }
    /* else we are prob on RPi 1 with BCM2835, and use the hardwired defaults */

    /* Now get ready to map the peripherals block 
     * If we are not root, try for the new /dev/gpiomem interface and accept
     * the fact that we can only access GPIO
     * else try for the /dev/mem interface and get access to everything
     */
    memfd = -1;
    ok = 0;
    if (geteuid() == 0) {
        /* Open the master /dev/mem device */
        if ((memfd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) {
            fprintf(stderr, "bcm2835_init: Unable to open /dev/mem: %s\n", strerror(errno));
            goto exit;
        }

        /* Base of the peripherals block is mapped to VM */
        bcm2835_peripherals = mapmem("gpio", bcm2835_peripherals_size, memfd, (off_t) bcm2835_peripherals_base);
        if (bcm2835_peripherals == MAP_FAILED) {
            goto exit;
        }

        /* Now compute the base addresses of various peripherals,
        // which are at fixed offsets within the mapped peripherals block
        // Caution: bcm2835_peripherals is uint32_t*, so divide offsets by 4
        */
        bcm2835_gpio = bcm2835_peripherals + BCM2835_GPIO_BASE / 4;
        bcm2835_pwm = bcm2835_peripherals + BCM2835_GPIO_PWM / 4;
        bcm2835_clk = bcm2835_peripherals + BCM2835_CLOCK_BASE / 4;
        bcm2835_pads = bcm2835_peripherals + BCM2835_GPIO_PADS / 4;
        bcm2835_spi0 = bcm2835_peripherals + BCM2835_SPI0_BASE / 4;
        bcm2835_bsc0 = bcm2835_peripherals + BCM2835_BSC0_BASE / 4; /* I2C */
        bcm2835_bsc1 = bcm2835_peripherals + BCM2835_BSC1_BASE / 4; /* I2C */
        bcm2835_st = bcm2835_peripherals + BCM2835_ST_BASE / 4;
        bcm2835_aux = bcm2835_peripherals + BCM2835_AUX_BASE / 4;
        bcm2835_spi1 = bcm2835_peripherals + BCM2835_SPI1_BASE / 4;

        ok = 1;
    } else {
        /* Not root, try /dev/gpiomem */
        /* Open the master /dev/mem device */
        if ((memfd = open("/dev/gpiomem", O_RDWR | O_SYNC)) < 0) {
            fprintf(stderr, "bcm2835_init: Unable to open /dev/gpiomem: %s\n", strerror(errno));
            goto exit;
        }

        /* Base of the peripherals block is mapped to VM */
        bcm2835_peripherals_base = 0;
        bcm2835_peripherals = mapmem("gpio", bcm2835_peripherals_size, memfd, (off_t) bcm2835_peripherals_base);
        if (bcm2835_peripherals == MAP_FAILED) {
            goto exit;
        }
        bcm2835_gpio = bcm2835_peripherals;
        ok = 1;
    }

    exit:
    if (memfd >= 0) {
        close(memfd);
    }

    if (!ok) {
        bcm2835_close();
    }

    return ok;
}

/* Close this library and deallocate everything */
int bcm2835_close(void)
{
    if (debug) {
        return 1;
    } /* Success */

    unmapmem((void**) &bcm2835_peripherals, bcm2835_peripherals_size);
    bcm2835_peripherals = MAP_FAILED;
    bcm2835_gpio = MAP_FAILED;
    bcm2835_pwm = MAP_FAILED;
    bcm2835_clk = MAP_FAILED;
    bcm2835_pads = MAP_FAILED;
    bcm2835_spi0 = MAP_FAILED;
    bcm2835_bsc0 = MAP_FAILED;
    bcm2835_bsc1 = MAP_FAILED;
    bcm2835_st = MAP_FAILED;
    bcm2835_aux = MAP_FAILED;
    bcm2835_spi1 = MAP_FAILED;
    return 1; /* Success */
}

#ifdef BCM2835_TEST
/* this is a simple test program that prints out what it will do rather than
// actually doing it
*/
int main(int argc, char **argv)
{
    /* Be non-destructive */
    bcm2835_set_debug(1);

    if (!bcm2835_init())
    return 1;

    /* Configure some GPIO pins fo some testing
    // Set RPI pin P1-11 to be an output
    */
    bcm2835_gpio_fsel(RPI_GPIO_P1_11, BCM2835_GPIO_FSEL_OUTP);
    /* Set RPI pin P1-15 to be an input */
    bcm2835_gpio_fsel(RPI_GPIO_P1_15, BCM2835_GPIO_FSEL_INPT);
    /*  with a pullup */
    bcm2835_gpio_set_pud(RPI_GPIO_P1_15, BCM2835_GPIO_PUD_UP);
    /* And a low detect enable */
    bcm2835_gpio_len(RPI_GPIO_P1_15);
    /* and input hysteresis disabled on GPIOs 0 to 27 */
    bcm2835_gpio_set_pad(BCM2835_PAD_GROUP_GPIO_0_27, BCM2835_PAD_SLEW_RATE_UNLIMITED|BCM2835_PAD_DRIVE_8mA);

        #if 1
    /* Blink */
    while (1)
    {
    /* Turn it on */
    bcm2835_gpio_write(RPI_GPIO_P1_11, HIGH);

    /* wait a bit */
    bcm2835_delay(500);

    /* turn it off */
    bcm2835_gpio_write(RPI_GPIO_P1_11, LOW);

    /* wait a bit */
    bcm2835_delay(500);
    }
        #endif

        #if 0
    /* Read input */
    while (1)
    {
    /* Read some data */
    uint8_t value = bcm2835_gpio_lev(RPI_GPIO_P1_15);
    printf("read from pin 15: %d\n", value);

    /* wait a bit */
    bcm2835_delay(500);
    }
        #endif

        #if 0
    /* Look for a low event detection
    // eds will be set whenever pin 15 goes low
    */
    while (1)
    {
    if (bcm2835_gpio_eds(RPI_GPIO_P1_15))
    {
        /* Now clear the eds flag by setting it to 1 */
        bcm2835_gpio_set_eds(RPI_GPIO_P1_15);
        printf("low event detect for pin 15\n");
    }

    /* wait a bit */
    bcm2835_delay(500);
    }
        #endif

    if (!bcm2835_close())
    return 1;

    return 0;
}
#endif



