Added VGA color example

Author: charliegreen

NOTES.MD

@@ -236,6 +236,35 @@ TODO: come up with good color values simulating the 8 terminal ANSI colors:
 |   6 | cyan    |     |
 |   7 | white   | ff  |
 
+Looking at the ANSI VGA RGB values:
+
+	255 -> 7 for 3-bit, 3 for 2-bit
+	170 -> 5 for 3-bit, 2 for 2-bit
+	85  -> 2 for 3-bit, 1 for 2-bit
+	0   -> 0 for 3-bit, 0 for 2-bit
+
+	low-intensity:
+	0:   0,   0,   0: 00 000 000: 00
+	1: 170,   0,   0: 00 000 101: 05
+	2:   0, 170,   0: 00 101 000: 28
+	3: 170,  85,   0: 00 010 101: 15
+	4:   0,   0, 170: 10 000 000: 80
+	5: 170,   0, 170: 10 000 101: 85
+	6:   0, 170, 170: 10 101 000: a8
+	7: 170, 170, 170: 10 101 101: ad
+
+	high-intensity:
+	0:  85,  85,  85: 01 010 010: 52
+	1: 255,  85,  85: 01 010 111: 57
+	2:  85, 255,  85: 01 111 010: 7a
+	3: 255, 255,  85: 01 111 111: 7f
+	4:  85,  85, 255: 11 010 010: d2
+	5: 255,  85, 255: 11 010 111: d7
+	6:  85, 255, 255: 11 111 010: fa
+	7: 255, 255, 255: 11 111 111: ff
+
+## older colors I had
+
 	colors: B- G-- R--
 	grey:   01 010 010: 0x52
 	blue:   11 000 000: 0xc0

README.md

@@ -1,4 +1,5 @@
 # mode96
+
 A video driver for the Uzebox.
 
 This is a codetile-based 36x28 video mode that can support up to 256 different 1bpp tiles, where
@@ -17,4 +18,8 @@ ASCII tileset (96 tiles), displayed with 12 of 16 possible different palettes:
 
 Scrambled VRAM, showing characters with 16 different palettes:
 
-![example 3](https://imgur.com/MB2Hu8H.png)
+![example 3](https://imgur.com/HkS2Qxu.png)
+
+A simulation of basic VGA colors from ANSI escape codes:
+
+![example 4](https://imgur.com/ChugAQ6.png)

main.c

@@ -4,16 +4,19 @@
 #include <avr/pgmspace.h>
 #include <uzebox.h>
 
+#include <stdio.h>
+
 /* EXAMPLES
  * 0: just for miscellaneous debugging code
  * 1: show ASCII with 12 different palettes
  * 2: show color values
  * 3: scramble VRAM
  * 4: fake terminal output (TODO, NYI)
  */
-#define EXAMPLE 1
+#define EXAMPLE 4
 
 ColorCombo m96_palette[16] = {
+#if EXAMPLE >= 0 && EXAMPLE < 4
     { 0xc0, 0x15 },		// blue on orange
     { 0x02, 0x10 }, 		// red on green
     { 0x83, 0x36 },		// violet on yellow
@@ -28,6 +31,27 @@ ColorCombo m96_palette[16] = {
     { 0xa7, 0xfd },
     { 0x39, 0x05 },
     { 0xff, 0x00 },
+
+#elif EXAMPLE == 4
+    // an imitation of ANSI color codes on a VGA display
+    { 0x00, 0x52 },		// low-intensity
+    { 0x05, 0x00 },
+    { 0x28, 0x00 },
+    { 0x15, 0x00 },
+    { 0x80, 0x00 },
+    { 0x85, 0x00 },
+    { 0xa8, 0x00 },
+    { 0xad, 0x00 },
+
+    { 0x52, 0x00 },		// high-intensity
+    { 0x57, 0x00 },
+    { 0x7a, 0x00 },
+    { 0x7f, 0x00 },
+    { 0xd2, 0x00 },
+    { 0xd7, 0x00 },
+    { 0xfa, 0x00 },
+    { 0xff, 0x00 },
+#endif
 };
 
 typedef struct {
@@ -45,12 +69,14 @@ void button_update() {
     _btn.prev = _btn.down;
 }
 
+#if EXAMPLE < 4
 static void palette_randomize() {
     for (u8 i = 0; i < 16; i++) {
 	m96_palette[i].fg = GetPrngNumber(0);
 	m96_palette[i].bg = GetPrngNumber(0);
     }
 }
+#endif
 
 #if EXAMPLE == 2
 static void palette_display() {
@@ -141,6 +167,37 @@ int main() {
 	}
     }
 
+#elif EXAMPLE == 4
+    Print(8, 0, PSTR("ANSI VGA simulation"));
+    Print(0, 2, PSTR("normal"));
+    Print(18, 2, PSTR("bright"));
+
+    for (u8 i = 0; i < SCREEN_TILES_H; i++)
+	for (u8 j = 0; j < SCREEN_TILES_V; j++)
+	    SetTileColor(i, j, 7);
+
+    u8 x = 0;
+    u8 line = 3;
+    char buf[18];
+    for (u8 color = 0; color < 16; color++) {
+	snprintf_P(buf, sizeof(buf), PSTR("%2d: color %2d: %02X"),
+		   color + (color > 7 ? 82 : 30), color,
+		   m96_palette[color].fg);
+
+	PrintRam(x, line, (unsigned char*)buf);
+	for (u8 i = 0; i < sizeof(buf); i++)
+	    SetTileColor(x+i, line, color);
+
+	line++;
+	if (color == 7) {
+	    x = 18;
+	    line = 3;
+	}
+    }
+
+    while (true)
+	WaitVsync(1);
+
 #else
 #error Unknown example
 #endif