island-ctory/src/vram.c

#include "vram.h"

#include <string.h>

#include "game.h"
#include "sdk/video.h"

mem_xfer_t mem_xfer_queue[MAX_XFERS];
uint8_t mem_xfer_queue_size;

void vram_init(void) { mem_xfer_queue_size = 0; }

static inline void vram_xfer_row(uint8_t *dest, const uint8_t *source,
                                 uint8_t size) {
    while (size > 0) {
        *dest++ = *source++;
        if ((uint8_t)dest % 32 == 0) {
            dest -= 32;
        }
        size--;
    }
}

static inline void vram_xfer_col(uint8_t *dest, const uint8_t *source,
                                 uint8_t size) {
    while (size > 0) {
        *dest = *source++;
        dest += SCRN_VX_B;
        if ((uint16_t)dest >= _SCRN1) {
            dest -= _SCRN1 - _SCRN0;
        }
        size--;
    }
}

void vram_update(void) {
    mem_xfer_t *xfer = &mem_xfer_queue[0];
    for (uint8_t i = 0; i < mem_xfer_queue_size; i++) {
        if (xfer->type == XFER_TYPE_ROW) {
            vram_xfer_row((uint8_t *)xfer->dest, xfer->source, xfer->size);
        } else {
            vram_xfer_col((uint8_t *)xfer->dest, xfer->source, xfer->size);
        }
        xfer++;
    }
    mem_xfer_queue_size = 0;
}