gba.c

/**
    @file gba.c
    @author Andrea Covre
    @version 1.3 (March 22nd, 2020)
*/

#include "gba.h"

volatile unsigned short *videoBuffer = (volatile unsigned short *)0x6000000;
u32 vBlankCounter = 0;

void waitForVBlank(void) {
  // preventing to count one VBlank more than once if the app is too fast
  while(SCANLINECOUNTER > 160);
  while(SCANLINECOUNTER < 160);
  vBlankCounter++;
}

static int __qran_seed = 42;
static int qran(void) {
  __qran_seed = 1664525 * __qran_seed + 1013904223;
  return (__qran_seed >> 16) & 0x7FFF;
}

int randint(int min, int max) { return (qran() * (max - min) >> 15) + min; }

void setPixel(int row, int col, u16 color) {
  videoBuffer[OFFSET(row, col, WIDTH)] = color;
}

void drawRectDMA(int row, int col, int width, int height, volatile u16 color) {
    for (int r = 0; r < height; r++) {
        DMA[3].src = &color;
        DMA[3].dst = &videoBuffer[OFFSET(row + r, col, 240)];
        DMA[3].cnt = width | DMA_ON | DMA_SOURCE_FIXED;
    }
}

void drawFullScreenImageDMA(const u16 *image) {
    for (int r = 0; r < 160; r++) {
        DMA[3].src = &image[OFFSET(r, 0, 240)];
        DMA[3].dst = &videoBuffer[OFFSET(r, 0, 240)];
        DMA[3].cnt = 240 | DMA_ON;
    }
}

void drawImageDMA(int row, int col, int width, int height, const u16 *image) {
  for (int r = 0; r < height; r++) {
      DMA[3].src = &image[OFFSET(r, 0, width)];
      DMA[3].dst = &videoBuffer[OFFSET(row + r, col, 240)];
      DMA[3].cnt = width | DMA_ON;
  }
}

void fillScreenDMA(volatile u16 color) {
  for (int r = 0; r < 160; r++) {
      DMA[3].src = &color;
      DMA[3].dst = &videoBuffer[OFFSET(r, 0, 240)];
      DMA[3].cnt = 240 | DMA_ON | DMA_SOURCE_FIXED;
  }
}

void drawChar(int row, int col, char ch, u16 color) {
  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 8; j++) {
      if (fontdata_6x8[OFFSET(j, i, 6) + ch * 48]) {
        setPixel(row + j, col + i, color);
      }
    }
  }
}

void drawString(int row, int col, char *str, u16 color) {
  while (*str) {
    drawChar(row, col, *str++, color);
    col += 6;
  }
}

void drawCenteredString(int row, int col, int width, int height, char *str,
    u16 color) {
        u32 len = 0;
        char *strCpy = str;
        while (*strCpy) {
            len++;
            strCpy++;
        }

  u32 strWidth = 6 * len;
  u32 strHeight = 8;

  int new_row = row + ((height - strHeight) >> 1);
  int new_col = col + ((width - strWidth) >> 1);
  drawString(new_row, new_col, str, color);
}