The Weird and The Wonderful

honey the codewitch wrote:

I am a stickler about namespace polution

jschell wrote:

The form suggested by the other response seems much more maintainable.

honey the codewitch wrote:

so I'm confused as to how you could say it was more maintainable having never seen it.

honey the codewitch wrote:

Furthermore, it is not feasible to limit said preprocessor macros to a single file as doing so would increase maintenance since several processors with their own instructions are presented, each in its own header. To combine them would create a monolithic header that included every single build target. No.

honey the codewitch wrote:

Finally, unit testing this is not feasible, as I don't have the money to set up the hardware array necessary to unit test this across all build targets

honey the codewitch wrote:

I did not write it that way, and I'm not rewriting six files of macros.

honey the codewitch wrote:

the *first* time I do it in the code.

M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
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if(pin_d0>31) {
    b = (pins_h>>(pin_d0&31))&1;
} else if(pin_d0>-1) {
    b = (pins_l>>pin_d0)&1;
} else {
    b=0;
}

const int NUM_BUS_BITS = 8;     // Dealing with an eight bit bus
const int NUM_GPIO_PINS = 40;   // ESP32 has GPIOs 0 to 39

// Last read state of the GPIO bus
static uint32_t sGPIOLow, sGPIOHigh;

// Map data bus to GPIO bits
static struct
{
    uint32_t* pSource;          // Which GPIO variable to use
    unsigned shift;             // Shift to apply for this bit
} sDataMap[NUM_BUS_BITS];

// Initialise mapping between input data bit and GPIO pin - call for each data bit prior to readInput()
static void mapInputPin(unsigned dataBit, unsigned gpioPin)
{
    if (dataBit < NUM_BUS_BITS && gpioPin < NUM_GPIO_PINS)
    {
        sDataMap[dataBit].pSource = gpioPin >= 32 ? &sGPIOHigh : &sGPIOLow;
        sDataMap[dataBit].shift = gpioPin & 31;
    }
}

// Read our eight bit bus value from the appropriate GPIO pins
static uint8_t readInput(void)
{
    // Read the hardware bus (the need for 3x reads should be investigated)
    sGPIOLow = gpio_input_get();
    sGPIOLow = gpio_input_get();
    sGPIOLow = gpio_input_get();
    sGPIOHigh = gpio_input_get_high();

    // Decode from GPIO to eight bit bus
    uint8_t dataRead = 0;
    dataRead |= (((*sDataMap[0].pSource) >> sDataMap[0].shift) & 1) << 0;
    dataRead |= (((*sDataMap[1].pSource) >> sDataMap[1].shift) & 1) << 1;
    dataRead |= (((*sDataMap[2].pSource) >> sDataMap[2].shift) & 1) << 2;
    dataRead |= (((*sDataMap[3].pSource) >> sDataMap[3].shift) & 1) << 3;
    dataRead |= (((*sDataMap[4].pSource) >> sDataMap[4].shift) & 1) << 4;
    dataRead |= (((*sDataMap[5].pSource) >> sDataMap[5].shift) & 1) << 5;
    dataRead |= (((*sDataMap[6].pSource) >> sDataMap[6].shift) & 1) << 6;
    dataRead |= (((*sDataMap[7].pSource) >> sDataMap[7].shift) & 1) << 7;

    return dataRead;
}

int main(void)
{
    // Initialise mapping for GPIO allocation
    // (Use defines or named constants for a real implementation)
    mapInputPin(0, 4);
    mapInputPin(1, 5);
    mapInputPin(2, 6);
    mapInputPin(3, 7);
    mapInputPin(4, 36);
    mapInputPin(5, 37);
    mapInputPin(6, 38);
    mapInputPin(7, 39);

    // Read input
    uint8_t readData = readInput();

    return readData;
}

// Data pin GPIO allocation - purely an example
const unsigned pin_d0 = 4;
const unsigned pin_d1 = 5;
const unsigned pin_d2 = 6;
const unsigned pin_d3 = 7;
const unsigned pin_d4 = 36;
const unsigned pin_d5 = 37;
const unsigned pin_d6 = 38;
const unsigned pin_d7 = 39;

// Read our eight bit bus value from the appropriate GPIO pins
static uint8_t readInput(void)
{
    // Add delay here

    // Read the hardware bus
    uint32_t GPIOLow = gpio_input_get();
    uint32_t GPIOHigh = gpio_input_get_high();

    // Decode from GPIO to eight bit bus
    uint8_t dataRead = 0;
    dataRead |= (((pin_d0 > 31 ? GPIOHigh : GPIOLow) >> (pin_d0 & 31)) & 1) << 0;
    dataRead |= (((pin_d1 > 31 ? GPIOHigh : GPIOLow) >> (pin_d1 & 31)) & 1) << 1;
    dataRead |= (((pin_d2 > 31 ? GPIOHigh : GPIOLow) >> (pin_d2 & 31)) & 1) << 2;
    dataRead |= (((pin_d3 > 31 ? GPIOHigh : GPIOLow) >> (pin_d3 & 31)) & 1) << 3;
    dataRead |= (((pin_d4 > 31 ? GPIOHigh : GPIOLow) >> (pin_d4 & 31)) & 1) << 4;
    dataRead |= (((pin_d5 > 31 ? GPIOHigh : GPIOLow) >> (pin_d5 & 31)) & 1) << 5;
    dataRead |= (((pin_d6 > 31 ? GPIOHigh : GPIOLow) >> (pin_d6 & 31)) & 1) << 6;
    dataRead |= (((pin_d7 > 31 ? GPIOHigh : GPIOLow) >> (pin_d7 & 31)) & 1) << 7;

    return dataRead;
}

if(pin_d1>31) {
        b |= (((pins_h>>((pin_d1-32)&31))&1)<<1);
    } else if(pin_d1>-1) {
        b |= (((pins_l>>(pin_d1))&1)<<1);
    }