initial commit

.gitignore

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+rgb555conv

README.md

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+# rgb555conv - converts 24 bit color to 15 bit color
+I got tired of manually converting 24 bit hex colors (like `0xRRGGBB`) into 15
+bit RGB555 colors (like `0b0BBBBBGGGGGRRRRR`) so I slapped this together to do
+it for me.  Be warned that the 4 character color it outputs is in BGR format
+instead of RGB for use on the Game Boy Color and Game Boy Advance. It also
+outputs a 24 bit representation of the 15 bit color (still in `0xRRGGBB`) for
+use in things like your sprite software.

UNLICENSE

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+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>

main.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+typedef struct {
+	uint8_t r;
+	uint8_t g;
+	uint8_t b;
+} rgb888;
+
+
+int main (int argc, char *argv[])
+{
+	if (argc != 2) {
+		printf("Please provide a single 24 bit color of the format `0xRRGGBB` as input.\n");
+		return 1;
+	}
+
+	uint32_t in_888 = strtol(argv[1], NULL, 16);
+
+	printf(" Input, 24 bit color, 6 char hex: #%06X\n\n", in_888);
+	
+	rgb888 split;
+	split.r = (in_888 & 0x00FF0000) >> 16;
+	split.g = (in_888 & 0x0000FF00) >> 8;
+	split.b = in_888 & 0x000000FF;
+
+	// Basic rounding
+	if (split.r & 4) split.r |= 8;
+	if (split.g & 4) split.g |= 8;
+	if (split.b & 4) split.b |= 8;
+
+	int16_t rgb555 = ((split.b & 0xF8) << 7) | ((split.g & 0xF8) << 2) | (split.r >> 3);
+
+	printf("Output, 15 bit color, 4 char hex:  0x%04X\n", rgb555);
+	printf("Output, 15 bit color, 6 char hex: #%06X\n", (uint32_t) ((split.r & 0xF8) << 16) | ((split.g & 0xF8) << 8) | (split.b & 0xF8));
+
+	return 0;
+}