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Record "seed" when generating images as well

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For reproducibility
This commit is contained in:
ISSOtm
2022-03-19 13:20:15 +01:00
committed by Eldred Habert
parent e753b62d1a
commit 7d54145e56
1 changed files with 27 additions and 7 deletions
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34
test/randtilegen.c
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@@ -22,25 +22,25 @@
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.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 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 uint8_t randCount = 0; // How many bits are currently stored in the above
size_t nbRandBytes = 0;
static uint32_t getRandomBits(uint8_t count) { static uint32_t getRandomBits(uint8_t count) {
// Trying to read one more byte with `randCount` at least this high will drop some bits // 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 will exit without reading more bytes // 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); assert(count <= sizeof(randBits) * 8 + 1);
// Read bytes until we have enough bits to serve the request // Read bytes until we have enough bits to serve the request
while (count > randCount) { while (count > randCount) {
int data = getchar(); int data = getchar();
if (data == EOF) { if (data == EOF) {
fprintf(stderr, "Exit after reading %zu bytes\n", nbRandBytes);
exit(0); exit(0);
} }
randBits |= (uint32_t)data << randCount; randBits |= (uint32_t)data << randCount;
randCount += 8; randCount += 8;
++nbRandBytes; fputc(data, rngRecorder);
} }
uint32_t result = randBits & (((uint32_t)1 << count) - 1); uint32_t result = randBits & (((uint32_t)1 << count) - 1);
@@ -49,6 +49,14 @@ static uint32_t getRandomBits(uint8_t count) {
return result; 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 * Expand a 5-bit color component to 8 bits with minimal bias
*/ */
@@ -203,10 +211,17 @@ int main(int argc, char **argv) {
} }
} }
char filename[maxBasenameLen + 25]; char filename[maxBasenameLen + sizeof("65535.png")];
for (uint16_t i = 0;; i++) { // 65k images ought to be enough for (uint16_t i = 0;; i++) { // 65k images ought to be enough
for (int index = 1; index < argc; index++) { for (int index = 1; index < argc; index++) {
sprintf(filename, "%s%" PRIu16 ".png", argv[index], i); 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"); FILE *img = fopen(filename, "wb");
if (!img) { if (!img) {
perror("PNG fopen"); perror("PNG fopen");
@@ -227,10 +242,15 @@ int main(int argc, char **argv) {
return 1; 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); png_init_io(png, img);
generate_random_image(png, pngInfo); generate_random_image(png, pngInfo);
png_destroy_write_struct(&png, &pngInfo); png_destroy_write_struct(&png, &pngInfo);
fclose(img); fclose(img);
fclose(rngRecorder);
} }
if (i == UINT16_MAX) { if (i == UINT16_MAX) {