cool-bun-demo/screen.c

#include "screen.h"
#include "types.h"

#include <clib/exec_protos.h>
#include <exec/memory.h>

/**
 * Includes double buffer space
 */
#define TOTAL_SCREEN_SETUP_SIZE(s) ((s->width / 8) * s->height * s->bitplanes * 2)

void setupScreen(
  struct ScreenSetup *screenSetup,
  uint16_t width,
  uint16_t height,
  uint8_t bitplanes
) {
  unsigned char *memory;

  screenSetup->width = width;
  screenSetup->height = height;
  screenSetup->bitplanes = bitplanes;

  memory = (unsigned char *)AllocMem(
    TOTAL_SCREEN_SETUP_SIZE(screenSetup),
    MEMF_CLEAR | MEMF_CHIP
  );

  screenSetup->memoryStart = memory;
  screenSetup->byteWidth = width / 8;

  // memory is not interleaved
  screenSetup->nextBitplaneAdvance = screenSetup->byteWidth * height;
  screenSetup->nextBufferAdvance = screenSetup->nextBitplaneAdvance * bitplanes;
}

void teardownScreen(
  struct ScreenSetup *screenSetup
) {
  FreeMem(
    screenSetup->memoryStart,
    TOTAL_SCREEN_SETUP_SIZE(screenSetup)
  );
}

void setCurrentScreen(
  struct ScreenSetup *screenSetup,
  struct CurrentScreen *currentScreen,
  short int buffer
) {
  int plane;
  currentScreen->currentBuffer = buffer;

  for (plane = 0; plane < screenSetup->bitplanes; ++plane) {
    currentScreen->planes[plane] = screenSetup->memoryStart +
      buffer * screenSetup->nextBufferAdvance +
      plane * screenSetup->nextBitplaneAdvance;
  }
}

void swapCurrentScreenBuffer(
  struct ScreenSetup *screenSetup,
  struct CurrentScreen *currentScreen
) {
  setCurrentScreen(screenSetup, currentScreen, 1 - currentScreen->currentBuffer);
}

void setupInitialCurrentScreen(
  struct ScreenSetup *screenSetup,
  struct CurrentScreen *currentScreen
) {
  setCurrentScreen(screenSetup, currentScreen, 0);
}