#include <stdint.h>


struct StepperInterface {
    uint32_t target_pos;
    uint32_t current_pos;
    uint32_t speed;
    bool halt_requested;
    bool moving;
};

far struct StepperInterface shmem __attribute__((location(0x000000))) = {};
//StepperInterface shmem __attribute__((cregister("LOCAL",near))) = {};


// define some r30 bits
#define CW  (1 << 3)
#define CCW (1 << 7)

volatile register uint32_t __R30;


#define delay_us(n) __delay_cycles((n) * 200u)
#define delay_ms(n) delay_us((n) * 1000u)

int main() {

    uint32_t pos = shmem.current_pos;
    __R30 = 0;
    delay_us(1);
    while ( !shmem.halt_requested ) {
        uint32_t speed = shmem.speed;
        int32_t delta = shmem.target_pos - pos;
        if ( delta == 0 ) {
            shmem.moving = false;
            continue;
        }
        if ( delta < 0 ) {
            --pos;
            __R30 |= CCW;
            delta *= -1;
            shmem.moving = true;
        } else {
            ++pos;
            __R30 |= CW;
            shmem.moving = true;
        }
        shmem.current_pos = pos;
            switch(speed){
                case 1:
                    delay_us(50);
                    __R30 = 0;
                    delay_us(50);
                    break;
                case 2:
                    delay_us(100);
                    __R30 = 0;
                    delay_us(100);
                    break;
                default:
                    delay_us(500);
                    __R30 = 0;
                    delay_us(500);
            }

    }
    __halt();
}