diff options
| -rw-r--r-- | Makefile | 6 | ||||
| -rw-r--r-- | TODO | 2 | ||||
| -rw-r--r-- | liblss16.h | 150 | ||||
| -rw-r--r-- | liblss16_decode_to_colour_index.c | 20 | ||||
| -rw-r--r-- | liblss16_encode_from_colour_index.c | 177 | ||||
| -rw-r--r-- | liblss16_encode_strerror.c | 21 | ||||
| -rw-r--r-- | liblss16_encoder_init.c | 46 | ||||
| -rw-r--r-- | liblss16_optimise.c | 80 | ||||
| -rw-r--r-- | lss16toppm.c | 14 |
9 files changed, 494 insertions, 22 deletions
@@ -22,7 +22,11 @@ BIN =\ OBJ_LIB =\ liblss16_decoder_init.o\ liblss16_decode_to_colour_index.o\ - liblss16_decode_strerror.o + liblss16_decode_strerror.o\ + liblss16_encoder_init.o\ + liblss16_encode_from_colour_index.o\ + liblss16_encode_strerror.o\ + liblss16_optimise.o OBJ =\ $(OBJ_LIB)\ @@ -1,3 +1,3 @@ -Write encoder +Write ppmtolss16 Write man pages Write README @@ -104,6 +104,51 @@ enum liblss16_decode_error { /** + * Image encoding state + */ +enum liblss16_encode_state { + /** + * Still encoding + */ + LIBLSS16_ENCODE_RUNNING, + + /** + * Encodig done + */ + LIBLSS16_ENCODE_DONE, + + /** + * Error occured while encoding + */ + LIBLSS16_ENCODE_ERROR +}; + + +/** + * Error values for image encoding + */ +enum liblss16_encode_error { + /** + * The image has zero width, zero height, + * or the height exceeds 32767 + */ + LIBLSS16_ENCODE_BAD_IMAGE_SIZE, + + /** + * User specified that colour were encoded in + * 6 bits, however at least one colour value + * had at least one of it it high bits set + */ + LIBLSS16_ENCODE_BAD_COLOUR, + + /** + * Colour index above 15 specified for a pixel + */ + LIBLSS16_ENCODE_BAD_COLOUR_INDEX +}; + + +/** * sRGB colour values, with transfer function applied, * encoded in values in [0, 255] */ @@ -126,9 +171,9 @@ struct liblss16_colour { /** - * Decode state + * Image header */ -struct liblss16_decoder { +struct liblss16_header { /** * The width of the raster */ @@ -143,7 +188,17 @@ struct liblss16_decoder { * Image colour map */ struct liblss16_colour colour_map[16]; +}; + +/** + * Decode state + */ +struct liblss16_decoder { + /** + * Image header + */ + struct liblss16_header image; /** * For internal use @@ -161,6 +216,23 @@ struct liblss16_decoder { /** + * Encode state + * + * Should be considered opaque + */ +struct liblss16_encoder { + struct liblss16_header header; + uint16_t x_rem; + uint16_t y_rem; + uint16_t repetition; + uint8_t header_position; + uint8_t previous; + uint8_t nbuffered; + uint8_t buffered[6]; +}; + + +/** * Initialise a decoder * * @param decoder The decoder @@ -169,6 +241,8 @@ void liblss16_decoder_init(struct liblss16_decoder *decoder); /** + * Decode an LSS16 file + * * @param decoder Decoder state, must have been initialised with * `liblss16_decoder_init` before the first call * @param data Data to decode image from (may be partial) @@ -179,7 +253,8 @@ void liblss16_decoder_init(struct liblss16_decoder *decoder); * for the pixels in the image. They are returned * primarily from to the top down and secondarily * from left to right. - * @param pixels_size The number of elements that may be stored in `pixels` + * @param pixels_size The number of elements that may be stored in `pixels`, + * must be at least 1 * @param npixels_out Output parameter for the number of elements stored * in `pixels`. Always set. * @param error_out Output parameter for the error; only set if @@ -213,4 +288,73 @@ __attribute__((__const__)) const char *liblss16_decode_strerror(enum liblss16_decode_error error); +/** + * Initialise an encoder + * + * @param encoder The encoder + * @param header Image information + * @param rgb6 If non-zero, colour values in `header->colour_map` are + * encoded in 6 bits (the limitation of the LSS16 format) + * rather than 8 bits + * @param error_out Output parameter for the error; only set when -1 is + * returned; may be `NULL` + * @return 0 on success, -1 on failure + */ +int liblss16_encoder_init(struct liblss16_encoder *encoder, const struct liblss16_header *header, + int rgb6, enum liblss16_encode_error *error_out); + + +/** + * Encode an LSS16 file + * + * @param encoder Encoder state, must have been initialised with + * `liblss16_encoder_init` before the first call + * @param buffer Output buffer for the image data + * @param size Size of `buffer` + * @param written_out The number of bytes written to `size`, must be at least 1 + * @param pixels Buffer with pixels to encode; the pixels are to preencoded + * (before the function is called) with the colour index of + * each pixel. Pixels are input primarily from to the top + * down and secondarily from left to right. + * @param npixels The number of provided pixels + * @param nconsumed_out Output parameter for the number of pixels consumed into + * to state of the encoder + * @param error_out Output parameter for the error; only set if + * `LIBLSS16_ENCODE_ERROR` is returned; may be `NULL` + * @return The processing state: normally `LIBLSS16_ENCODE_RUNNING`, + * but `LIBLSS16_ENCODE_DONE` when the image has been + * fully encoded, and `LIBLSS16_ENCODE_ERROR` on error + */ +enum liblss16_encode_state liblss16_encode_from_colour_index( + struct liblss16_encoder *encoder, void *buffer, size_t size, + size_t *written_out, const uint8_t *pixels, size_t npixels, + size_t *nconsumed_out, enum liblss16_encode_error *error_out); + + +/** + * Get error description for an error code + * + * @param error The error code + * @return The error description + */ +#if defined(__GNUC__) +__attribute__((__const__)) +#endif +const char *liblss16_encode_strerror(enum liblss16_encode_error error); + + +/** + * Optimise and image + * + * @param header The image metadata + * @param pixel Buffer with pixels; the pixels are to encoded with the + * colour index of each pixel. Pixels are encoded primarily + * from to the top down and secondarily from left to right. + * + * Both `pixels` and `header->colour_map` may be rewritten + * (to an equivalent image with at least as good compression with LSS16) + */ +void liblss16_optimise(struct liblss16_header *header, uint8_t *pixels); + + #endif diff --git a/liblss16_decode_to_colour_index.c b/liblss16_decode_to_colour_index.c index 3d184c2..a552289 100644 --- a/liblss16_decode_to_colour_index.c +++ b/liblss16_decode_to_colour_index.c @@ -85,7 +85,7 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, /* fall through */ case 4: - decoder->width = (uint16_t)*data++; + decoder->image.width = (uint16_t)*data++; ++*consumed_out; ++decoder->internal.init_state; if (!--length) @@ -93,7 +93,7 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, /* fall through */ case 5: - decoder->width |= (uint16_t)((uint16_t)*data++ << 8); + decoder->image.width |= (uint16_t)((uint16_t)*data++ << 8); ++*consumed_out; ++decoder->internal.init_state; if (!--length) @@ -101,7 +101,7 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, /* fall through */ case 6: - decoder->height = (uint16_t)*data++; + decoder->image.height = (uint16_t)*data++; ++*consumed_out; ++decoder->internal.init_state; if (!--length) @@ -109,13 +109,13 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, /* fall through */ case 7: - decoder->height |= (uint16_t)((uint16_t)*data++ << 8); + decoder->image.height |= (uint16_t)((uint16_t)*data++ << 8); ++*consumed_out; ++decoder->internal.init_state; - decoder->internal.x_rem = decoder->width; - decoder->internal.y_rem = decoder->height; - if (!decoder->width || !decoder->height || decoder->height >> 15) { + decoder->internal.x_rem = decoder->image.width; + decoder->internal.y_rem = decoder->image.height; + if (!decoder->image.width || !decoder->image.height || decoder->image.height >> 15) { if (error_out) *error_out = LIBLSS16_DECODE_BAD_IMAGE_SIZE; return LIBLSS16_DECODE_ERROR; @@ -131,13 +131,13 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, uint8_t value = *data++; ++*consumed_out; if (value & 0xC0) { - ((uint8_t *)decoder->colour_map)[i] = value; + ((uint8_t *)decoder->image.colour_map)[i] = value; if (error_out) *error_out = LIBLSS16_DECODE_BAD_COLOUR; return LIBLSS16_DECODE_ERROR; } else { value = (uint8_t)(((unsigned)value * 255U + 31U) / 63U); - ((uint8_t *)decoder->colour_map)[i] = value; + ((uint8_t *)decoder->image.colour_map)[i] = value; } if (!--length) @@ -184,7 +184,7 @@ liblss16_decode_to_colour_index(struct liblss16_decoder *decoder, } decoder->internal.x_rem -= m; if (!decoder->internal.x_rem) { - decoder->internal.x_rem = decoder->width; + decoder->internal.x_rem = decoder->image.width; decoder->internal.y_rem--; if (decoder->internal.saved > 1U) { if (error_out) diff --git a/liblss16_encode_from_colour_index.c b/liblss16_encode_from_colour_index.c new file mode 100644 index 0000000..1efff36 --- /dev/null +++ b/liblss16_encode_from_colour_index.c @@ -0,0 +1,177 @@ +/* See LICENSE file for copyright and license details. */ +#include "liblss16.h" +#include <string.h> +#include <stdlib.h> + + +static size_t +flush_buffer(struct liblss16_encoder *encoder, uint8_t *buffer, size_t size) +{ + size_t i; + for (i = 0; size && encoder->nbuffered - i > 1U; i += 2U, size--) + buffer[i] = (uint8_t)(encoder->buffered[i + 0] | (encoder->buffered[i + 1] << 4)); + memmove(&encoder->buffered[0], &encoder->buffered[i], encoder->nbuffered - i); + return i; +} + + +enum liblss16_encode_state +liblss16_encode_from_colour_index(struct liblss16_encoder *encoder, void *buffer_, size_t size, + size_t *written_out, const uint8_t *pixels, size_t npixels, + size_t *nconsumed_out, enum liblss16_encode_error *error_out) +{ + uint8_t *buffer = buffer_; + size_t n; + + *written_out = 0; + *nconsumed_out = 0; + + switch (encoder->header_position) { + case 0: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)0x3DU; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 1: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)0xF3U; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 2: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)0x13U; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 3: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)0x14U; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 4: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)encoder->header.width; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 5: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)(encoder->header.width >> 8); + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 6: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)encoder->header.height; + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + case 7: + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = (uint8_t)(encoder->header.height >> 8); + ++*nconsumed_out; + encoder->header_position++; + /* fall through */ + + default: + break; + } + + while (encoder->header_position < 8U + 16U * 3U) { + if (!size--) + return LIBLSS16_ENCODE_RUNNING; + *buffer++ = ((const uint8_t *)encoder->header.colour_map)[encoder->header_position++]; + ++*nconsumed_out; + encoder->header_position++; + } + + if (encoder->nbuffered > 1U) { + n = flush_buffer(encoder, buffer, size); + buffer = &buffer[n]; + size -= n; + *written_out += n; + if (encoder->nbuffered > 1U) + return LIBLSS16_ENCODE_RUNNING; + if (!encoder->y_rem) { + if (encoder->nbuffered) + abort(); + return LIBLSS16_ENCODE_DONE; + } + } + + while (npixels--) { + if (*pixels == encoder->previous) { + encoder->repetition++; + } else if (*pixels > 15U) { + if (error_out) + *error_out = LIBLSS16_ENCODE_BAD_COLOUR_INDEX; + return LIBLSS16_ENCODE_ERROR; + } else { + if (!encoder->repetition) { + /* do nothing */ + } else if (encoder->repetition < 16U) { + encoder->buffered[encoder->nbuffered++] = encoder->previous; + encoder->buffered[encoder->nbuffered++] = (uint8_t)encoder->repetition; + } else { + unsigned value = encoder->repetition - 16U; + encoder->buffered[encoder->nbuffered++] = encoder->previous; + encoder->buffered[encoder->nbuffered++] = 0; + encoder->buffered[encoder->nbuffered++] = (uint8_t)(value & 15U); + encoder->buffered[encoder->nbuffered++] = (uint8_t)(value >> 4); + } + encoder->buffered[encoder->nbuffered++] = *pixels; + encoder->previous = *pixels; + encoder->repetition = 0; + + n = flush_buffer(encoder, buffer, size); + buffer = &buffer[n]; + size -= n; + *written_out += n; + if (encoder->nbuffered > 1U) + return LIBLSS16_ENCODE_RUNNING; + } + ++pixels; + ++*nconsumed_out; + + if (!--encoder->x_rem) { + encoder->previous = 0; + encoder->repetition = 0; + encoder->x_rem = encoder->header.width; + encoder->y_rem--; + if (encoder->nbuffered & 1) + encoder->buffered[encoder->nbuffered++] = 0; + + n = flush_buffer(encoder, buffer, size); + buffer = &buffer[n]; + size -= n; + *written_out += n; + if (encoder->nbuffered > 1U) + return LIBLSS16_ENCODE_RUNNING; + else if (encoder->nbuffered) + abort(); + + if (!encoder->y_rem) + return LIBLSS16_ENCODE_DONE; + } + } + + return LIBLSS16_ENCODE_RUNNING; +} diff --git a/liblss16_encode_strerror.c b/liblss16_encode_strerror.c new file mode 100644 index 0000000..a5fcd49 --- /dev/null +++ b/liblss16_encode_strerror.c @@ -0,0 +1,21 @@ +/* See LICENSE file for copyright and license details. */ +#include "liblss16.h" + + +const char * +liblss16_encode_strerror(enum liblss16_encode_error error) +{ + switch (error) { + case LIBLSS16_ENCODE_BAD_IMAGE_SIZE: + return "Unencodable image: unsupported image size"; + + case LIBLSS16_ENCODE_BAD_COLOUR: + return "Invalid colour map: 6-bit colours encoded with additional bits"; + + case LIBLSS16_ENCODE_BAD_COLOUR_INDEX: + return "Invalid image: colour index out of range"; + + default: + return "Unrecognised error"; + } +} diff --git a/liblss16_encoder_init.c b/liblss16_encoder_init.c new file mode 100644 index 0000000..037cd8e --- /dev/null +++ b/liblss16_encoder_init.c @@ -0,0 +1,46 @@ +/* See LICENSE file for copyright and license details. */ +#include "liblss16.h" +#include <string.h> + + +int +liblss16_encoder_init(struct liblss16_encoder *encoder, const struct liblss16_header *header, + int rgb6, enum liblss16_encode_error *error_out) +{ + int i; + + memset(encoder, 0, sizeof(*encoder)); + memcpy(&encoder->header, header, sizeof(*header)); + + if (!encoder->header.width || !encoder->header.height || encoder->header.height >> 15) { + if (error_out) + *error_out = LIBLSS16_ENCODE_BAD_IMAGE_SIZE; + return -1; + } + + if (rgb6) { + uint8_t or = 0; + for (i = 0; i < 16; i++) { + or |= encoder->header.colour_map[i].r; + or |= encoder->header.colour_map[i].g; + or |= encoder->header.colour_map[i].b; + } + if (or & 0xC0) { + if (error_out) + *error_out = LIBLSS16_ENCODE_BAD_COLOUR; + return -1; + } + } else { + struct liblss16_colour *map = encoder->header.colour_map; + for (i = 0; i < 16; i++) { + map[i].r = (uint8_t)(((unsigned)map[i].r * 63U + 127U) / 255U); + map[i].g = (uint8_t)(((unsigned)map[i].g * 63U + 127U) / 255U); + map[i].b = (uint8_t)(((unsigned)map[i].b * 63U + 127U) / 255U); + } + } + + encoder->x_rem = encoder->header.width; + encoder->y_rem = encoder->header.height; + + return 0; +} diff --git a/liblss16_optimise.c b/liblss16_optimise.c new file mode 100644 index 0000000..911fcd2 --- /dev/null +++ b/liblss16_optimise.c @@ -0,0 +1,80 @@ +/* See LICENSE file for copyright and license details. */ +#include "liblss16.h" +#include <string.h> + + +void +liblss16_optimise(struct liblss16_header *header, uint8_t *pixels) +{ + uint8_t remap[16], unmap[16], ncolours, colour, preferred; + unsigned x, y, count, width; + size_t p, n; + int32_t zero[16], nonzero[16]; + int32_t zero_penalty, least; + + for (x = 0; x < 16U; x++) { + remap[x] = (uint8_t)x; + unmap[x] = 0; + } + + memset(zero, 0, sizeof(zero)); + memset(nonzero, 0, sizeof(nonzero)); + + for (x = 0; x < 15U; x++) { + if (unmap[x]) + continue; + header->colour_map[ncolours++] = header->colour_map[x]; + for (y = x + 1U; y < 16U; y++) { + if (header->colour_map[y].r != header->colour_map[x].r || + header->colour_map[y].g != header->colour_map[x].g || + header->colour_map[y].b != header->colour_map[x].b) + continue; + unmap[y] = 1; + remap[y] = ncolours; + } + } + + width = (unsigned)header->width; + width = width < 17U ? width : 17U; + for (y = 0, p = 0; y < (unsigned)header->height; y++) { + colour = remap[pixels[p]]; + count = 1U; + for (x = 1U; x < width; x++, p++) { + if (remap[pixels[p]] != colour) + break; + count += 1U; + } + p += (size_t)header->width - (size_t)x; + zero[colour] += count < 16U ? 2 : 3; + nonzero[colour] += count == 1 ? 1 : count < 17 ? 3 : 4; + } + + least = zero[0] - nonzero[0]; + preferred = 0U; + for (x = 1U; x < (unsigned)ncolours; x++) { + zero_penalty = zero[x] - nonzero[x]; + if (zero_penalty < least) { + least = zero_penalty; + preferred = (uint8_t)x; + } + } + + if (preferred) { + struct liblss16_colour tc; + uint8_t t8; + tc = header->colour_map[preferred]; + header->colour_map[preferred] = header->colour_map[0]; + header->colour_map[0] = tc; + t8 = remap[preferred]; + remap[preferred] = remap[0]; + remap[0] = t8; + } + + n = p; + for (n = p, p = 0; p < n; p++) + pixels[p] = remap[pixels[p]]; + + memset(&header->colour_map[ncolours], + header->colour_map[ncolours - 1U].b, + (16U - ncolours) * sizeof(*header->colour_map)); +} diff --git a/lss16toppm.c b/lss16toppm.c index db4d448..6dcff62 100644 --- a/lss16toppm.c +++ b/lss16toppm.c @@ -92,14 +92,14 @@ main(int argc, char *argv[]) if (!head_printed) { head_printed = 1; - len = sprintf(wbuf, "P6\n%u %u\n255\n", decoder.width, decoder.height); + len = sprintf(wbuf, "P6\n%u %u\n255\n", decoder.image.width, decoder.image.height); if (len < 0 || (size_t)len >= sizeof(wbuf)) abort(); pending = (size_t)len; if (print_colour_map) { - for (i = 0; i < sizeof(decoder.colour_map) / sizeof(*decoder.colour_map); i++) { - fprintf(stderr, "#%02x%02x%02x=%zu\n", decoder.colour_map[i].r, - decoder.colour_map[i].g, decoder.colour_map[i].b, i); + for (i = 0; i < sizeof(decoder.image.colour_map) / sizeof(*decoder.image.colour_map); i++) { + fprintf(stderr, "#%02x%02x%02x=%zu\n", decoder.image.colour_map[i].r, + decoder.image.colour_map[i].g, decoder.image.colour_map[i].b, i); } } } @@ -108,9 +108,9 @@ main(int argc, char *argv[]) writeall(wbuf, pending); pending = 0; } - wbuf[pending++] = (char)decoder.colour_map[pixels[i]].r; - wbuf[pending++] = (char)decoder.colour_map[pixels[i]].g; - wbuf[pending++] = (char)decoder.colour_map[pixels[i]].b; + wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].r; + wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].g; + wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].b; } } } |