Added palette.c/h and palette_init() call in main.c

src/main.c

@@ -1,4 +1,4 @@
-/** 
+/**
  * Copyright (c) 2014 rxi
  *
  * This library is free software; you can redistribute it and/or modify it
@@ -16,6 +16,7 @@
 #include "luaobj.h"
 #include "keyboard.h"
 #include "image.h"
+#include "palette.h"
 
 
 static lua_State *L;
@@ -43,6 +44,7 @@ int main(void) {
   /* Init everything */
   atexit(deinit);
   vga_init();
+  palette_init();
   keyboard_init();
 
   /* Init lua */
@@ -99,4 +101,4 @@ int main(void) {
   }
 
   return 0;
-} 
+}

src/palette.c

@@ -0,0 +1,77 @@
+#include <stdlib.h>
+#include <pc.h>
+
+#include "palette.h"
+
+#define MAX_IDX   256
+#define MAP_SIZE  1024
+#define MAP_MASK  (MAP_SIZE - 1)
+
+static struct { unsigned color; int idx; } map[MAP_SIZE];
+static int nextIdx;
+static int inited;
+
+
+void palette_init(void) {
+  if (inited) return;
+  palette_reset();
+  inited = 1;
+}
+
+
+void palette_reset(void) {
+  /* Reset nextIdx -- start at idx 1 as 0 is used for transparency */
+  nextIdx = 1;
+  /* Reset map */
+  int i;
+  for (i = 0; i < MAP_SIZE; i++) {
+    map[i].idx = -1;
+  }
+}
+
+
+static unsigned hash(const void *data, int size) {
+  unsigned hash = 5381;
+  const unsigned char *p = data;
+  while (size--) {
+    hash = ((hash << 5) + hash) ^ *p++;
+  }
+  return hash;
+}
+
+
+int palette_colorIdx(int r, int g, int b) {
+  palette_init();
+
+  /* Make 18bit rgb color (6bits per-channel) from 8bit channels  */
+  unsigned color = ((r & 0xfc) << 10) | ((g & 0xfc) << 4) | ((b & 0xfc) >> 2);
+
+  /* Hash color */
+  unsigned h = hash(&color, sizeof(color));
+
+  /* Find color in hashmap */
+  int i = h & MAP_MASK;
+  while (map[i].idx != -1) {
+    if (map[i].color == color) {
+      return map[i].idx;
+    }
+    i = (i + 1) & MAP_MASK;
+  }
+
+  /* Color wasn't found in hashmap -- Add to system palette and map */
+  if (nextIdx >= MAX_IDX) {
+    return -1;  /* Return -1 for error if we've exceeded the palette capacity */
+  }
+  int idx = nextIdx++;
+
+  /* Update system palette */
+  outp(0x03c8, idx);
+  outp(0x03c9, (color      ) & 0x3f); /* r */
+  outp(0x03c9, (color >>  6) & 0x3f); /* g */
+  outp(0x03c9, (color >> 12) & 0x3f); /* b */
+
+  /* Add to hashmap and return idx */
+  map[i].color = color;
+  map[i].idx = idx;
+  return idx;
+}

src/palette.h

@@ -0,0 +1,8 @@
+#ifndef PALETTE_H
+#define PALETTE_H
+
+void palette_init(void);
+void palette_reset(void);
+int palette_colorIdx(int r, int g, int b);
+
+#endif