| 1 | #include <stdint.h> |
| 2 | #include <stddef.h> |
| 3 | #include <lib/qoi.h> |
| 4 | #include <lib/misc.h> |
| 5 | #include <mm/pmm.h> |
| 6 | |
| 7 | #define QOI_OP_INDEX 0x00 |
| 8 | #define QOI_OP_DIFF 0x40 |
| 9 | #define QOI_OP_LUMA 0x80 |
| 10 | #define QOI_OP_RUN 0xc0 |
| 11 | #define QOI_OP_RGB 0xfe |
| 12 | #define QOI_OP_RGBA 0xff |
| 13 | #define QOI_OP_MASK 0xc0 |
| 14 | #define QOI_HEADER_SIZE 14 |
| 15 | #define QOI_PADDING_SIZE 8 |
| 16 | #define QOI_MAX_DIM 65536u |
| 17 | #define QOI_MAX_PIXELS ((size_t)400000000) |
| 18 | #define QOI_HASH(r, g, b, a) \ |
| 19 | ((((unsigned)(r) * 3u) + ((unsigned)(g) * 5u) + \ |
| 20 | ((unsigned)(b) * 7u) + ((unsigned)(a) * 11u)) & 63u) |
| 21 | |
| 22 | static uint32_t qoi_be32(const uint8_t *p) { |
| 23 | return ((uint32_t)p[0] << 24) | ((uint32_t)p[1] << 16) | |
| 24 | ((uint32_t)p[2] << 8) | (uint32_t)p[3]; |
| 25 | } |
| 26 | |
| 27 | /* The decoded buffer is laid out as [total_bytes][padding to 16][pixels...]. |
| 28 | The 16-byte header lets qoi_free() recover the original allocation size |
| 29 | without the caller having to track it. */ |
| 30 | static uint32_t *qoi_alloc_xrgb(size_t pixels) { |
| 31 | size_t bytes = CHECKED_MUL(pixels, (size_t)4, return NULL); |
| 32 | size_t total = CHECKED_ADD(bytes, (size_t)16, return NULL); |
| 33 | void *raw = ext_mem_alloc(total); |
| 34 | *(size_t *) raw = total; |
| 35 | return (uint32_t *)((uint8_t *) raw + 16); |
| 36 | } |
| 37 | |
| 38 | void qoi_free(uint8_t *buf) { |
| 39 | if (buf) { uint8_t *raw = buf - 16; pmm_free(raw, *(size_t *) raw); } |
| 40 | } |
| 41 | |
| 42 | uint8_t *qoi_decode(const void *src, size_t src_size, |
| 43 | int *out_w, int *out_h) { |
| 44 | if (!src || src_size < QOI_HEADER_SIZE + QOI_PADDING_SIZE) return NULL; |
| 45 | const uint8_t * p = src; |
| 46 | if (p[0] != 'q' || p[1] != 'o' || p[2] != 'i' || p[3] != 'f') |
| 47 | return NULL; |
| 48 | uint32_t w = qoi_be32(p + 4), h = qoi_be32(p + 8); |
| 49 | uint8_t channels = p[12]; /* p[13] is the colorspace tag, ignored. */ |
| 50 | if (w == 0 || h == 0 || w > QOI_MAX_DIM || h > QOI_MAX_DIM) return NULL; |
| 51 | if (channels != 3 && channels != 4) return NULL; |
| 52 | size_t pixels = CHECKED_MUL((size_t)w, (size_t)h, return NULL); |
| 53 | if (pixels > QOI_MAX_PIXELS) return NULL; |
| 54 | uint32_t *out = qoi_alloc_xrgb(pixels); |
| 55 | if (out == NULL) return NULL; |
| 56 | uint32_t index[64] = { 0 }, v; int run = 0, dg; |
| 57 | uint8_t r = 0, g = 0, b = 0, a = 0xff, b2; |
| 58 | size_t pos = QOI_HEADER_SIZE, end = src_size - QOI_PADDING_SIZE; |
| 59 | for (size_t px = 0; px < pixels; px++) { |
| 60 | if (run > 0) run--; else { |
| 61 | if (pos >= end) goto fail; |
| 62 | uint8_t op = p[pos++]; |
| 63 | if (op == QOI_OP_RGB) { |
| 64 | if (end - pos < 3) goto fail; |
| 65 | r = p[pos++]; g = p[pos++]; b = p[pos++]; |
| 66 | } else if (op == QOI_OP_RGBA) { |
| 67 | if (end - pos < 4) goto fail; |
| 68 | r = p[pos++]; g = p[pos++]; b = p[pos++]; a = p[pos++]; |
| 69 | } else switch (op & QOI_OP_MASK) { |
| 70 | case QOI_OP_INDEX: |
| 71 | v = index[op & 0x3f]; |
| 72 | r = v; g = v >> 8; b = v >> 16; a = v >> 24; |
| 73 | break; |
| 74 | case QOI_OP_DIFF: |
| 75 | r += (int)((op >> 4) & 3u) - 2; |
| 76 | g += (int)((op >> 2) & 3u) - 2; |
| 77 | b += (int)( op & 3u) - 2; |
| 78 | break; |
| 79 | case QOI_OP_LUMA: |
| 80 | if (pos >= end) goto fail; |
| 81 | b2 = p[pos++]; |
| 82 | dg = (int)(op & 0x3f) - 32; |
| 83 | r += dg + (int)((b2 >> 4) & 0xf) - 8; |
| 84 | g += dg; |
| 85 | b += dg + (int)( b2 & 0xf) - 8; |
| 86 | break; |
| 87 | case QOI_OP_RUN: run = op & 0x3f; break; |
| 88 | } |
| 89 | index[QOI_HASH(r, g, b, a)] = |
| 90 | (uint32_t)r | ((uint32_t)g << 8) | |
| 91 | ((uint32_t)b << 16) | ((uint32_t)a << 24); |
| 92 | } |
| 93 | out[px] = ((uint32_t)r << 16) | ((uint32_t)g << 8) | (uint32_t)b; |
| 94 | } |
| 95 | *out_w = (int)w; *out_h = (int)h; return (uint8_t *) out; |
| 96 | fail: |
| 97 | qoi_free((uint8_t *) out); return NULL; |
| 98 | } |
