ref: ef473de75aa6fc25bf142141b470f867ec6d009f
dir: /test/randtilegen.c/
/*
* This file is part of RGBDS.
*
* Copyright (c) 2022, Eldred Habert and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*
* Originally:
* // This program is hereby released to the public domain.
* // ~aaaaaa123456789, released 2022-03-15
* https://gist.github.com/aaaaaa123456789/3feccf085ab4f82d144d9a47fb1b4bdf
*
* This was modified to use libpng instead of libplum, as well as comments and style changes.
*/
#include <assert.h>
#include <inttypes.h>
#include <limits.h>
#include <png.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "helpers.h"
FILE *rngRecorder; // File to which the random bytes will be read
uint32_t randBits = 0; // Storage for bits read from the input stream but not yet used
uint8_t randCount = 0; // How many bits are currently stored in the above
static uint32_t getRandomBits(uint8_t count) {
// Trying to read one more byte with `randCount` at least this high will drop some bits!
// If the count is no higher than that limit, then the loop is guaranteed to exit without
// reading more bytes.
assert(count <= sizeof(randBits) * 8 + 1);
// Read bytes until we have enough bits to serve the request
while (count > randCount) {
int data = getchar();
if (data == EOF) {
exit(0);
}
randBits |= (uint32_t)data << randCount;
randCount += 8;
fputc(data, rngRecorder);
}
uint32_t result = randBits & (((uint32_t)1 << count) - 1);
randBits >>= count;
randCount -= count;
return result;
}
/**
* Flush any remaining bits in the RNG storage
*/
static void flushRng(void) {
randCount = 0;
randBits = 0;
}
/**
* Expand a 5-bit color component to 8 bits with minimal bias
*/
static uint8_t _5to8(uint8_t five) {
return five << 3 | five >> 2;
}
struct Attribute {
unsigned char palette;
unsigned char nbColors;
};
#define NB_TILES 10 * 10
static void writePng(png_structp png, png_infop pngInfo, uint8_t width, uint8_t height, uint16_t palettes[][4], struct Attribute const *attributes, uint8_t tileData[][8][8]) {
uint8_t const nbTiles = width * height;
png_set_IHDR(png, pngInfo, width * 8, height * 8, 8, PNG_COLOR_TYPE_RGB_ALPHA,
getRandomBits(1) ? PNG_INTERLACE_NONE : PNG_INTERLACE_ADAM7,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
// While it would be nice to write the image little by little, I really don't want to handle
// interlacing myself. (We're doing interlacing to test that RGBGFX correctly handles it.)
uint8_t const SIZEOF_PIXEL = 4; // Each pixel is 4 bytes (RGBA @ 8 bits/component)
uint8_t data[height * 8 * width * 8 * SIZEOF_PIXEL];
uint8_t *rowPtrs[height * 8];
for (uint8_t y = 0; y < height * 8; ++y) {
rowPtrs[y] = &data[y * width * 8 * SIZEOF_PIXEL];
}
for (uint8_t p = 0; p < nbTiles; p++) {
uint8_t tx = 8 * (p % width), ty = 8 * (p / width);
for (uint8_t y = 0; y < 8; y++) {
uint8_t * const row = rowPtrs[ty + y];
for (uint8_t x = 0; x < 8; x++) {
uint8_t * const pixel = &row[(tx + x) * SIZEOF_PIXEL];
uint16_t color = palettes[attributes[p].palette][tileData[p][y][x]];
pixel[0] = _5to8(color & 0x1F);
pixel[1] = _5to8(color >> 5 & 0x1F);
pixel[2] = _5to8(color >> 10 & 0x1F);
pixel[3] = color & 0x8000 ? 0x00 : 0xFF;
}
}
}
png_set_rows(png, pngInfo, rowPtrs);
png_write_png(png, pngInfo, PNG_TRANSFORM_IDENTITY, NULL);
}
static void generate_random_image(png_structp png, png_infop pngInfo) {
struct Attribute attributes[NB_TILES];
uint8_t tileData[NB_TILES][8][8];
// These two are in tiles, not pixels, and in range [3; 10], hence `NB_TILES` above
// Both width and height are 4-bit values, so nbTiles is 8-bit (OK!)
uint8_t const width = getRandomBits(3) + 3, height = getRandomBits(3) + 3,
nbTiles = width * height;
for (uint8_t p = 0; p < nbTiles; p++) {
uint8_t pal;
do {
pal = getRandomBits(5);
} while (pal == 0 || (pal > 29));
attributes[p].palette = 2 * pal + getRandomBits(1);
// Population count (nb of bits set), the simple way
static uint8_t const popcount[] = {1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4};
attributes[p].nbColors = popcount[pal - 1];
// Handle single-color tiles the simple way, without trying to pull more random bits
if (attributes[p].nbColors < 2) {
memset(tileData[p], 0, sizeof(tileData[p]));
continue;
}
uint8_t index, total;
for (index = 0, total = 0; index < p; index++) {
if (attributes[index].nbColors == attributes[p].nbColors) {
total++;
}
}
// index == p at exit
if (total) {
index = getRandomBits(8);
if (index < total) {
total = index + 1;
for (index = 0; total; index++) {
if (attributes[index].nbColors == attributes[p].nbColors) {
total--;
}
if (!total) {
index--;
}
}
} else {
index = p;
}
}
if (index != p) {
unsigned rotation = getRandomBits(2);
for (uint8_t y = 0; y < 8; y++) {
for (uint8_t x = 0; x < 8; x++) {
tileData[p][y][x] =
tileData[index][y ^ ((rotation & 2) ? 7 : 0)][x ^ ((rotation & 1) ? 7 : 0)];
}
}
} else {
switch (attributes[p].nbColors) {
case 2: // Two-color tiles only need one random bit per pixel
for (uint8_t y = 0; y < 8; y++)
for (uint8_t x = 0; x < 8; x++)
tileData[p][y][x] = getRandomBits(1);
break;
case 4: // 4-color tiles can use two random bits per pixel
for (uint8_t y = 0; y < 8; y++)
for (uint8_t x = 0; x < 8; x++)
tileData[p][y][x] = getRandomBits(2);
break;
case 3: // 3-color tiles must draw two random bits, but reject them if out of range
for (uint8_t y = 0; y < 8; y++) {
for (uint8_t x = 0; x < 8; x++) {
do {
index = getRandomBits(2);
} while (index == 3);
tileData[p][y][x] = index;
}
}
break;
default: // 1-color tiles were handled earlier
unreachable_();
}
}
}
uint16_t colors[10];
for (uint8_t p = 0; p < 10; p++) {
colors[p] = getRandomBits(15);
}
// Randomly make color #0 of all palettes transparent
if (!getRandomBits(2)) {
colors[0] |= 0x8000;
colors[5] |= 0x8000;
}
uint16_t palettes[60][4];
for (uint8_t p = 0; p < 60; p++) {
uint16_t const *subpal = &colors[p & 1 ? 5 : 0];
uint8_t total = 0;
for (uint8_t index = 0; index < 5; index++) {
if (p & (2 << index)) {
palettes[p][total++] = subpal[index];
}
}
}
writePng(png, pngInfo, width, height, palettes, attributes, tileData);
}
int main(int argc, char **argv) {
if (argc < 2) {
fputs("usage: randtilegen <basename> [<basename> [...]]\n", stderr);
return 2;
}
size_t maxBasenameLen = 0;
for (int index = 1; index < argc; index++) {
size_t length = strlen(argv[index]);
if (length > maxBasenameLen) {
maxBasenameLen = length;
}
}
char filename[maxBasenameLen + sizeof("65535.png")];
for (uint16_t i = 0;; i++) { // 65k images ought to be enough
for (int index = 1; index < argc; index++) {
int len = sprintf(filename, "%s%" PRIu16 ".rng", argv[index], i);
rngRecorder = fopen(filename, "wb");
if (!rngRecorder) {
perror("RNG fopen");
return 1;
}
filename[len - 3] = 'p'; // `.rng` -> `.png`
FILE *img = fopen(filename, "wb");
if (!img) {
perror("PNG fopen");
return 1;
}
png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png) {
perror("png_create_write_struct");
return 1;
}
png_infop pngInfo = png_create_info_struct(png);
if (!pngInfo) {
perror("png_create_info_struct");
return 1;
}
if (setjmp(png_jmpbuf(png))) {
fprintf(stderr, "FATAL: an error occurred while writing image \"%s\"\n", filename);
return 1;
}
// Ensure that image generation starts on byte boundaries
// (This is necessary so that all involved random bits are recorded in the `.rng` file)
flushRng();
png_init_io(png, img);
generate_random_image(png, pngInfo);
png_destroy_write_struct(&png, &pngInfo);
fclose(img);
fclose(rngRecorder);
}
if (i == UINT16_MAX) {
break;
}
}
}