diff options
| -rw-r--r-- | bin/pngo.c | 132 |
1 files changed, 66 insertions, 66 deletions
diff --git a/bin/pngo.c b/bin/pngo.c index a2575422..47a7ad80 100644 --- a/bin/pngo.c +++ b/bin/pngo.c @@ -17,6 +17,7 @@ #include <arpa/inet.h> #include <assert.h> #include <err.h> +#include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> @@ -220,100 +221,96 @@ enum PACKED FilterType { FILT_PAETH, }; -static uint8_t paethPredictor(uint8_t a, uint8_t b, uint8_t c) { - int32_t p = (int32_t)a + (int32_t)b - (int32_t)c; - int32_t pa = labs(p - (int32_t)a); - int32_t pb = labs(p - (int32_t)b); - int32_t pc = labs(p - (int32_t)c); - if (pa <= pb && pa <= pc) return a; - if (pb <= pc) return b; - return c; +struct FilterBytes { + uint8_t x; + uint8_t a; + uint8_t b; + uint8_t c; +}; + +static uint8_t paethPredictor(struct FilterBytes f) { + int32_t p = (int32_t)f.a + (int32_t)f.b - (int32_t)f.c; + int32_t pa = labs(p - (int32_t)f.a); + int32_t pb = labs(p - (int32_t)f.b); + int32_t pc = labs(p - (int32_t)f.c); + if (pa <= pb && pa <= pc) return f.a; + if (pb <= pc) return f.b; + return f.c; } -static uint8_t recon( - enum FilterType type, - uint8_t x, uint8_t a, uint8_t b, uint8_t c -) { +static uint8_t recon(enum FilterType type, struct FilterBytes f) { switch (type) { - case FILT_NONE: return x; - case FILT_SUB: return x + a; - case FILT_UP: return x + b; - case FILT_AVERAGE: return x + ((uint32_t)a + (uint32_t)b) / 2; - case FILT_PAETH: return x + paethPredictor(a, b, c); + case FILT_NONE: return f.x; + case FILT_SUB: return f.x + f.a; + case FILT_UP: return f.x + f.b; + case FILT_AVERAGE: return f.x + ((uint32_t)f.a + (uint32_t)f.b) / 2; + case FILT_PAETH: return f.x + paethPredictor(f); } } -static uint8_t filt( - enum FilterType type, - uint8_t x, uint8_t a, uint8_t b, uint8_t c -) { +static uint8_t filt(enum FilterType type, struct FilterBytes f) { switch (type) { - case FILT_NONE: return x; - case FILT_SUB: return x - a; - case FILT_UP: return x - b; - case FILT_AVERAGE: return x - ((uint32_t)a + (uint32_t)b) / 2; - case FILT_PAETH: return x - paethPredictor(a, b, c); + case FILT_NONE: return f.x; + case FILT_SUB: return f.x - f.a; + case FILT_UP: return f.x - f.b; + case FILT_AVERAGE: return f.x - ((uint32_t)f.a + (uint32_t)f.b) / 2; + case FILT_PAETH: return f.x - paethPredictor(f); } } struct Scanline { enum FilterType *type; - uint8_t *ptr; + uint8_t *data; }; -static void reconData(const char *path, struct Header header, uint8_t *data) { - uint8_t bpp = bytesPerPixel(header); - uint32_t stride = 1 + bpp * header.width; +static struct Scanline *scanlines( + const char *path, struct Header header, uint8_t *data +) { + struct Scanline *lines = malloc(header.height * sizeof(*lines)); + if (!lines) err(EX_OSERR, "malloc(%zu)", header.height * sizeof(*lines)); - struct Scanline lines[header.height]; + uint32_t stride = 1 + bytesPerPixel(header) * header.width; for (uint32_t y = 0; y < header.height; ++y) { lines[y].type = &data[y * stride]; - lines[y].ptr = &data[y * stride + 1]; + lines[y].data = &data[y * stride + 1]; if (*lines[y].type > FILT_PAETH) { errx(EX_DATAERR, "%s: invalid filter type %hhu", path, *lines[y].type); } } + return lines; +} + +static struct FilterBytes filterBytes( + const struct Scanline *lines, uint8_t bpp, + uint32_t y, uint32_t i +) { + bool a = (i >= bpp), b = (y > 0), c = (a && b); + return (struct FilterBytes) { + .x = lines[y].data[i], + .a = a ? lines[y].data[i - bpp] : 0, + .b = b ? lines[y - 1].data[i] : 0, + .c = c ? lines[y - 1].data[i - bpp] : 0, + }; +} + +static void reconData(struct Header header, const struct Scanline *lines) { + uint8_t bpp = bytesPerPixel(header); for (uint32_t y = 0; y < header.height; ++y) { - for (uint32_t x = 0; x < header.width; ++x) { - for (uint8_t i = 0; i < bpp; ++i) { - lines[y].ptr[x * bpp + i] = recon( - *lines[y].type, - lines[y].ptr[x * bpp + i], - x ? lines[y].ptr[(x - 1) * bpp + i] : 0, - y ? lines[y - 1].ptr[x * bpp + i] : 0, - (x && y) ? lines[y - 1].ptr[(x - 1) * bpp + i] : 0 - ); - } + for (uint32_t i = 0; i < bpp * header.width; ++i) { + lines[y].data[i] = recon(*lines[y].type, filterBytes(lines, bpp, y, i)); } *lines[y].type = FILT_NONE; } } -static void filterData(struct Header header, uint8_t *data) { +static void filterData(struct Header header, const struct Scanline *lines) { uint8_t bpp = bytesPerPixel(header); - uint32_t stride = 1 + bpp * header.width; - - struct Scanline lines[header.height]; - for (uint32_t y = 0; y < header.height; ++y) { - lines[y].type = &data[y * stride]; - lines[y].ptr = &data[y * stride + 1]; - assert(*lines[y].type == FILT_NONE); - } - for (uint32_t y = header.height - 1; y < header.height; --y) { - for (uint32_t x = header.width - 1; x < header.width; --x) { - for (uint8_t i = 0; i < bpp; ++i) { - // TODO: Filter type heuristic. - *lines[y].type = FILT_PAETH; - lines[y].ptr[x * bpp + i] = filt( - FILT_PAETH, - lines[y].ptr[x * bpp + i], - x ? lines[y].ptr[(x - 1) * bpp + i] : 0, - y ? lines[y - 1].ptr[x * bpp + i] : 0, - (x && y) ? lines[y - 1].ptr[(x - 1) * bpp + i] : 0 - ); - } + // TODO: Filter type heuristic. + *lines[y].type = FILT_PAETH; + for (uint32_t i = (bpp * header.width) - 1; i < bpp * header.width; ++i) { + lines[y].data[i] = filt(*lines[y].type, filterBytes(lines, bpp, y, i)); } } } @@ -388,12 +385,13 @@ int main(int argc, char *argv[]) { } uint8_t *data = readData(path, file, header); + struct Scanline *lines = scanlines(path, header, data); - reconData(path, header, data); + reconData(header, lines); // TODO: "Optimize". - filterData(header, data); + filterData(header, lines); // TODO: -o path = "stdout"; @@ -406,4 +404,6 @@ int main(int argc, char *argv[]) { int error = fclose(file); if (error) err(EX_IOERR, "%s", path); + + // TODO: Free lines, data. } |