#include <stdint.h>


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

far struct StepperInterface shmem __attribute__((location(0x10100))) = {};
//StepperInterface shmem __attribute__((cregister("LOCAL",near))) = {};


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

volatile register uint32_t __R30;


#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(1000);
        deassert_CW_CCW();
        delay_us(1000);
    }
    __halt();
}