clem_scc.c

#include "clem_debug.h"
#include "clem_device.h"
#include "clem_mmio_defs.h"
#include "clem_mmio_types.h"

#define CLEM_SCC_STATE_REGISTER_WAIT     0
#define CLEM_SCC_STATE_REGISTER_SELECTED 1

void clem_scc_reset(struct ClemensDeviceSCC *scc) {}

void clem_scc_glu_sync(struct ClemensDeviceSCC *scc, struct ClemensClock *clock) {
    scc->ts_last_frame = clock->ts;
}

void clem_scc_write_switch(struct ClemensDeviceSCC *scc, uint8_t ioreg, uint8_t value) {

    switch (ioreg) {
    case CLEM_MMIO_REG_SCC_B_CMD:
    case CLEM_MMIO_REG_SCC_A_CMD:
        break;
    case CLEM_MMIO_REG_SCC_B_DATA:
    case CLEM_MMIO_REG_SCC_A_DATA:
        if (scc->state == CLEM_SCC_STATE_REGISTER_WAIT) {
            scc->selected_reg[CLEM_MMIO_REG_SCC_A_DATA - ioreg] = value;
            scc->state = CLEM_SCC_STATE_REGISTER_SELECTED;
        } else {
            scc->state = CLEM_SCC_STATE_REGISTER_WAIT;
        }
        break;
    }
    // CLEM_LOG("clem_scc: %02X <- %02X", ioreg, value);
}

uint8_t clem_scc_read_switch(struct ClemensDeviceSCC *scc, uint8_t ioreg, uint8_t flags) {
    uint8_t value = 0;
    bool is_noop = (flags & CLEM_OP_IO_NO_OP) != 0;
    switch (ioreg) {
    case CLEM_MMIO_REG_SCC_B_CMD:
    case CLEM_MMIO_REG_SCC_A_CMD:
        break;
    case CLEM_MMIO_REG_SCC_B_DATA:
    case CLEM_MMIO_REG_SCC_A_DATA:
        break;
    }
    // if (!is_noop) {
    //     CLEM_LOG("clem_scc: %02X -> %02X", ioreg, value);
    // }
    return value;
}