First commit

Signed-off-by: Mattias Andrée <m@maandree.se>

1 files changed, 221 insertions, 0 deletions

diff --git a/liblss16_decode_to_colour_index.c b/liblss16_decode_to_colour_index.c
new file mode 100644
index 0000000..3d184c2
--- /dev/null
+++ b/liblss16_decode_to_colour_index.c
@@ -0,0 +1,221 @@
+/* See LICENSE file for copyright and license details. */
+#include "liblss16.h"
+#include <string.h>
+
+
+enum liblss16_decode_state
+liblss16_decode_to_colour_index(struct liblss16_decoder *decoder,
+                                const void *data_, size_t length, size_t *consumed_out,
+                                uint8_t *pixels, size_t pixels_size, size_t *npixels_out,
+                                enum liblss16_decode_error *error_out)
+{
+	const uint8_t *data = data_;
+	uint8_t n;
+	uint16_t m;
+	size_t cnt;
+
+	*consumed_out = 0;
+	*npixels_out = 0;
+
+	if (decoder->internal.kept) {
+		while (decoder->internal.kept && pixels_size) {
+			*pixels++ = decoder->internal.previous;
+			--decoder->internal.kept;
+			--pixels_size;
+			++*npixels_out;
+		}
+		if (decoder->internal.kept)
+			return LIBLSS16_DECODE_RUNNING;
+	}
+
+	if (!length) {
+		enum liblss16_decode_error error;
+		if (decoder->internal.init_state < 4U)
+			error = LIBLSS16_DECODE_TRUNCATED_MAGIC;
+		else if (decoder->internal.init_state < 8U + 16U * 3U)
+			error = LIBLSS16_DECODE_TRUNCATED_HEADER;
+		else if (!decoder->internal.y_rem)
+			return LIBLSS16_DECODE_END_OF_IMAGE;
+		else
+			error = LIBLSS16_DECODE_TRUNCATED_IMAGE;
+		if (error_out)
+			*error_out = error;
+		return LIBLSS16_DECODE_ERROR;
+	}
+
+	switch (decoder->internal.init_state) {
+	case 0:
+		if (*data++ != 0x3DU) {
+		bad_magic:
+			if (error_out)
+				*error_out = LIBLSS16_DECODE_BAD_MAGIC;
+			return LIBLSS16_DECODE_ERROR;
+		}
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 1:
+		if (*data++ != 0xF3U)
+			goto bad_magic;
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 2:
+		if (*data++ != 0x13U)
+			goto bad_magic;
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 3:
+		if (*data++ != 0x14U)
+			goto bad_magic;
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 4:
+		decoder->width = (uint16_t)*data++;
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 5:
+		decoder->width |= (uint16_t)((uint16_t)*data++ << 8);
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 6:
+		decoder->height = (uint16_t)*data++;
+		++*consumed_out;
+		++decoder->internal.init_state;
+		if (!--length)
+			break;
+		/* fall through */
+
+	case 7:
+		decoder->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) {
+			if (error_out)
+				*error_out = LIBLSS16_DECODE_BAD_IMAGE_SIZE;
+			return LIBLSS16_DECODE_ERROR;
+		}
+
+		if (!--length)
+			break;
+		/* fall through */
+
+	default:
+		while (decoder->internal.init_state < 8U + 16U * 3U) {
+			size_t i = decoder->internal.init_state++ - 8U;
+			uint8_t value = *data++;
+			++*consumed_out;
+			if (value & 0xC0) {
+				((uint8_t *)decoder->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;
+			}
+
+			if (!--length)
+				return LIBLSS16_DECODE_RUNNING;
+		}
+
+		for (;;) {
+			if (!decoder->internal.y_rem)
+				return LIBLSS16_DECODE_END_OF_IMAGE;
+
+			if (decoder->internal.saved) {
+				n = (uint8_t)(decoder->internal.saved - 1U);
+				decoder->internal.saved = 0;
+			} else {
+				uint8_t high, low;
+				if (!pixels_size || !length)
+					return LIBLSS16_DECODE_RUNNING;
+				high = (uint8_t)(*data >> 4);
+				low = (uint8_t)(*data & 15);
+				n = low;
+				decoder->internal.saved = (uint8_t)(high + 1U);
+				++data;
+				--length;
+				++*consumed_out;
+			}
+
+			if (decoder->internal.state == 0U) {
+				if (n != decoder->internal.previous) {
+					decoder->internal.previous = n;
+					m = 1U;
+					goto put_m_pixels;
+				} else {
+					decoder->internal.state = 1U;
+				}
+			} else if (decoder->internal.state == 1U) {
+				if (n) {
+					m = (uint16_t)n;
+				put_m_pixels:
+					decoder->internal.state = 0U;
+					if (m > decoder->internal.x_rem) {
+						if (error_out)
+							*error_out = LIBLSS16_DECODE_EXCESSIVE_RUN_LENGTH;
+						return LIBLSS16_DECODE_ERROR;
+					}
+					decoder->internal.x_rem -= m;
+					if (!decoder->internal.x_rem) {
+						decoder->internal.x_rem = decoder->width;
+						decoder->internal.y_rem--;
+						if (decoder->internal.saved > 1U) {
+							if (error_out)
+								*error_out = LIBLSS16_DECODE_BAD_ROW_PADDING;
+							return LIBLSS16_DECODE_ERROR;
+						}
+						decoder->internal.saved = 0;
+						decoder->internal.previous = 0;
+					}
+					cnt = (size_t)m < pixels_size ? (size_t)m : pixels_size;
+					memset(pixels, decoder->internal.previous, cnt);
+					pixels = &pixels[cnt];
+					pixels_size -= cnt;
+					*npixels_out += cnt;
+					m -= (uint16_t)cnt;
+					if (m) {
+						decoder->internal.kept = m;
+						return LIBLSS16_DECODE_RUNNING;
+					}
+				} else {
+					decoder->internal.state = 2U;
+				}
+			} else if (decoder->internal.state == 2U) {
+				decoder->internal.state = (uint8_t)(n | 128U);
+			} else {
+				m = (uint16_t)((n << 4) + (decoder->internal.state & 15U) + 16U);
+				goto put_m_pixels;
+			}
+		}
+		break;
+	}
+
+	return LIBLSS16_DECODE_RUNNING;
+}