#include <stdint.h>
#include <stddev.h>

#include "sys_gpio.h"
struct StepperInterface {
    uint32_t target_pos;
    uint32_t current_pos;
    bool halt_requested;
};
StepperInterface shmem __attribute__((cregister("LOCAL", near))) = {};
volatile register uint32_t __R30;

// define some r30 bits
#define CW  (1u << 0)
#define CCW (1u << 1)

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

static inline void deassert_CW_CCW() { __R30 = 0; }
static inline void assert_CW() { __R30 = CW; }
static inline void assert_CCW() { __R30 = CCW; }

int main() {
        uint32_t pos = shmem.current_pos;
        deassert_CW_CCW();
        delay_us(1);

        while ( !shmem.halt_requested ) {
                int32_t delta = shmem.target_pos - pos;
                if ( delta == 0 )
                        continue;
                if ( delta < 0 ) {
                        --pos;
                        assert_CCW();
                } else {
                        ++pos;
                        assert_CW();
                }

                shmem.current_pos = pos;
                delay_us(1);
                deassert_CW_CCW();
                delay_us(1);
        }
        __halt();
}