136 lines
3.4 KiB
C
136 lines
3.4 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <malloc.h>
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#include <dos.h>
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#include "bmp_loader.h"
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#include "pc_stuff.h"
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#include "vga.h"
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int readBMPHeader(FILE *fh, struct BMPImage *info) {
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int sizeOfHeader;
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unsigned int numberOfUsedColors;
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if ((fgetc(fh) != 'B') || (fgetc(fh) != 'M')) {
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printf("Not a BMP file\n");
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return 1;
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}
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fseek(fh, 12, SEEK_CUR);
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fread(&sizeOfHeader, sizeof(int), 1, fh);
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fread(&info->width, sizeof(int), 1, fh);
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fread(&info->height, sizeof(int), 1, fh);
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fseek(fh, 2, SEEK_CUR);
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fread(&info->bpp, sizeof(word), 1, fh);
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// for gimp, you need to add colors to the color map until it hits
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// 16 colors, then the image will be a 256 color, 8 bpp image
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//
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// https://www.gimp-forum.net/Thread-indexing-into-8-bit?pid=13233#pid13233
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if (info->bpp != 8) return 1;
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fseek(fh, 16, SEEK_CUR);
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fread(&numberOfUsedColors, sizeof(unsigned int), 1, fh);
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if (numberOfUsedColors > 256) return 1;
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// get down to color data
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fseek(fh, 14 + sizeOfHeader, SEEK_SET);
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fread(info->colors, sizeof(struct BMPColor), numberOfUsedColors, fh);
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return 0;
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}
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int readBMPIntoMemory(FILE *fh, struct BMPImage *info) {
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int x, y, plane;
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int result;
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byte *currentPointer;
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result = readBMPHeader(fh, info);
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if (result) return result;
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currentPointer = info->memoryStart;
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for (y = 0; y < info->height; ++y) {
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for (x = 0; x < info->width; ++x) {
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currentPointer[(info->height - 1 - y) * info->width + x] = fgetc(fh);
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}
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}
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return 0;
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}
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int readBMPIntoUnchainedMemory(FILE *fh, struct BMPImage* info) {
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int x, y, plane;
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int writeX, writeY, offset;
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int unchainedLineWidth;
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int result;
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byte *rowHolder;
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result = readBMPHeader(fh, info);
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if (result) return result;
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unchainedLineWidth = info->width / 4;
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// reserve a row's worth of data
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// read the bitmap data into the row, interleaving for planes
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// for each plane, memcpy the data to the plane
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for (y = 0; y < info->height; ++y) {
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writeY = ((info->height - 1) - y) * unchainedLineWidth;
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for (x = 0; x < info->width; ++x) {
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plane = x & 0x03;
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writeX = (x >> 2);
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offset = plane * (unchainedLineWidth * info->height);
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info->memoryStart[offset + writeY + writeX] = fgetc(fh);
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}
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}
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return 0;
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}
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int readBMPIntoUnchainedVGAMemory(FILE *fh, struct BMPImage* info) {
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int x, y, plane;
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int unchainedLineWidth;
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int result;
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byte *rowHolder;
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result = readBMPHeader(fh, info);
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if (result) return result;
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rowHolder = malloc(info->width);
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unchainedLineWidth = info->width / 4;
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// reserve a row's worth of data
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// read the bitmap data into the row, interleaving for planes
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// for each plane, memcpy the data to the plane
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for (y = 0; y < info->height; ++y) {
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for (x = 0; x < info->width; ++x) {
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rowHolder[((x & 3) * 80) + (x >> 2)] = fgetc(fh);
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}
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for (plane = 0; plane < 4; ++plane) {
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setActiveVGAMemoryPlanes(1 << plane);
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memcpy(info->memoryStart + ((info->height - 1) - y) * info->width / 4, rowHolder + unchainedLineWidth * plane, unchainedLineWidth);
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}
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}
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free(rowHolder);
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return 0;
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}
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void bmp256ColorPaletteToVGAColorPalette(struct BMPImage* bmpImage, struct VGAColor colors[]) {
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int i;
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for (i = 0; i < 256; ++i) {
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colors[i].red = bmpImage->colors[i].red >> 2;
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colors[i].green = bmpImage->colors[i].green >> 2;
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colors[i].blue = bmpImage->colors[i].blue >> 2;
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}
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}
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