M src/shell/imgview.c → src/shell/imgview.c

@@ -7,6 +7,50 @@ #define GMODE_TEXT 0x02
 #define GMODE_VIDEO 0x13
 
 #define MAX(x, y) (x > y ? x : y)
+#define MIN(x, y) (x < y ? x : y)
+
+typedef struct __attribute__((packed)) {
+    uint16_t signature;
+    uint32_t file_size;
+    uint16_t reserved_1;
+    uint16_t reserved_2;
+    uint32_t offset_pixelarray;
+} BMP_FILE_HEADER;
+
+typedef struct {
+    uint32_t DIB_header_size;
+    uint32_t image_width;
+    uint32_t image_height;
+    /* ... */
+} DIB_HEADER;
+
+uint32_t convert_endian(uint32_t value) {
+    uint32_t res = 0;
+
+    return value;
+
+    for (int i = 0; i < 2; i++) {
+        uint8_t c = value & 0x0000FFFF;
+        value = value >> 16;
+        res = res << 16;
+        res |= c;
+    }
+
+    return res;
+}
+
+void draw_image(uint8_t *imgbuff, int off_x, int off_y, int width, int height) {
+    uint8_t *gbuff = (uint8_t*)(0xA0000);
+
+    for (int x = 0; x < MIN(width, 320); x++) {
+        for (int y = 0; y < MIN(height, 240); y++) {
+            int img_i = (height - y) * width + x;
+            int g_i = y * 320 + x;
+
+            gbuff[g_i] = imgbuff[img_i];
+        }
+    }
+}
 
 void main(char *args) {
     // open image file
@@ -22,14 +66,22 @@
     int size = sc_file_read(fd, fbuff, -1);
     int limit = 320 * 240;
 
-    uint8_t *gbuff = (uint8_t*)(0xA0000);
+    BMP_FILE_HEADER *bmp_header = (BMP_FILE_HEADER*)(fbuff);
+    DIB_HEADER *dib_header = (DIB_HEADER*)(&(bmp_header[1]));
+
+    int offset = bmp_header->offset_pixelarray;
+    int width = dib_header->image_width;
+    int height = dib_header->image_height;
+
+    uint8_t *imgbuff = fbuff + offset;
+
+    int off_x = 0;
+    int off_y = 0;
 
     // switch video mode and display image
     graphics_set_mode(GMODE_VIDEO);
 
-    for (int i = 0; i < MAX(size, limit); i++) {
-        gbuff[i] = fbuff[i];
-    }
+    draw_image(imgbuff, off_x, off_y, width, height);
 
     while (1) {
         char c;