19541344273

Committed 20 Nov 2025 03:02PM UTC coverage: 40.773% (-0.4%) from 41.21%

Build # 19541344273

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push

github

Committed by

saitoha

Commit Message

feat: initial prototyping for parallel dithering

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9711 of 33880 branches covered (28.66%)

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0.0

/src/dither-positional-float32.c

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright (c) 2025 libsixel developers. See `AUTHORS`.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "config.h"

#if HAVE_MATH_H
# include <math.h>
#endif  /* HAVE_MATH_H */
#include <string.h>

#include "dither-positional-float32.h"
#include "dither-common-pipeline.h"
#include "pixelformat.h"

static void
sixel_dither_scanline_params(int serpentine,
                             int index,
                             int limit,
                             int *start,
                             int *end,
                             int *step,
                             int *direction)
{
    if (serpentine && (index & 1)) {
        *start = limit - 1;
        *end = -1;
        *step = -1;
        *direction = -1;
    } else {
        *start = 0;
        *end = limit;
        *step = 1;
        *direction = 1;
    }
}

static float
mask_a(int x, int y, int c)
{
    return ((((x + c * 67) + y * 236) * 119) & 255) / 128.0f - 1.0f;
}

static float
mask_x(int x, int y, int c)
{
    return ((((x + c * 29) ^ (y * 149)) * 1234) & 511) / 256.0f - 1.0f;
}

SIXELSTATUS
sixel_dither_apply_positional_float32(sixel_dither_t *dither,
                                      sixel_dither_context_t *context)
{
#if _MSC_VER
    enum { max_channels = 4 };
#else
    const int max_channels = 4;
#endif
    int serpentine;
    int y;
    int absolute_y;
    float (*f_mask)(int x, int y, int c);
    float jitter_scale;
    float *palette_float;
    float *new_palette_float;
    int float_depth;
    int float_index;
    unsigned char *quantized;
    float lookup_pixel_float[max_channels];
    unsigned char const *lookup_pixel;
    int lookup_wants_float;
    int use_palette_float_lookup;
    int need_float_pixel;

    palette_float = NULL;
    new_palette_float = NULL;
    float_depth = 0;
    quantized = NULL;
    lookup_wants_float = 0;

    if (dither == NULL || context == NULL) {
        return SIXEL_BAD_ARGUMENT;
    }
    if (context->pixels_float == NULL || context->scratch == NULL) {
        return SIXEL_BAD_ARGUMENT;
    }
    if (context->palette == NULL || context->result == NULL) {
        return SIXEL_BAD_ARGUMENT;
    }

    switch (context->method_for_diffuse) {
    case SIXEL_DIFFUSE_A_DITHER:
        f_mask = mask_a;
        break;
    case SIXEL_DIFFUSE_X_DITHER:
    default:
        f_mask = mask_x;
        break;
    }

    serpentine = (context->method_for_scan == SIXEL_SCAN_SERPENTINE);
    jitter_scale = 32.0f / 255.0f;
    palette_float = context->palette_float;
    new_palette_float = context->new_palette_float;
    float_depth = context->float_depth;
    quantized = context->scratch;
    lookup_wants_float = (context->lookup_source_is_float != 0);
    use_palette_float_lookup = 0;
    if (context->prefer_palette_float_lookup != 0
            && palette_float != NULL
            && float_depth >= context->depth) {
        use_palette_float_lookup = 1;
    }
    need_float_pixel = lookup_wants_float || use_palette_float_lookup;

    if (context->optimize_palette) {
        int x;

        *context->ncolors = 0;
        memset(context->new_palette, 0x00,
               (size_t)SIXEL_PALETTE_MAX * (size_t)context->depth);
        if (new_palette_float != NULL && float_depth > 0) {
            memset(new_palette_float, 0x00,
                   (size_t)SIXEL_PALETTE_MAX
                       * (size_t)float_depth * sizeof(float));
        }
        memset(context->migration_map, 0x00,
               sizeof(unsigned short) * (size_t)SIXEL_PALETTE_MAX);
        for (y = 0; y < context->height; ++y) {
            absolute_y = context->band_origin + y;
            int start;
            int end;
            int step;
            int direction;

            sixel_dither_scanline_params(serpentine, absolute_y,
                                         context->width,
                                         &start, &end, &step, &direction);
            (void)direction;
            for (x = start; x != end; x += step) {
                int pos;
                int d;
                int color_index;

                pos = y * context->width + x;
                for (d = 0; d < context->depth; ++d) {
                    float val;

                    val = context->pixels_float[pos * context->depth + d]
                        + f_mask(x, y, d) * jitter_scale;
                    val = sixel_pixelformat_float_channel_clamp(
                        context->pixelformat,
                        d,
                        val);
                    if (need_float_pixel) {
                        lookup_pixel_float[d] = val;
                    }
                    if (!lookup_wants_float && !use_palette_float_lookup) {
                        quantized[d]
                            = sixel_pixelformat_float_channel_to_byte(
                                  context->pixelformat,
                                  d,
                                  val);
                    }
                }
                if (lookup_wants_float) {
                    lookup_pixel = (unsigned char const *)(void const *)
                        lookup_pixel_float;
                    color_index = context->lookup(lookup_pixel,
                                                  context->depth,
                                                  context->palette,
                                                  context->reqcolor,
                                                  context->indextable,
                                                  context->complexion);
                } else if (use_palette_float_lookup) {
                    color_index = sixel_dither_lookup_palette_float32(
                        lookup_pixel_float,
                        context->depth,
                        palette_float,
                        context->reqcolor,
                        context->complexion);
                } else {
                    lookup_pixel = quantized;
                    color_index = context->lookup(lookup_pixel,
                                                  context->depth,
                                                  context->palette,
                                                  context->reqcolor,
                                                  context->indextable,
                                                  context->complexion);
                }
                if (context->migration_map[color_index] == 0) {
                    if (absolute_y >= context->output_start) {
                        context->result[pos] = *context->ncolors;
                    }
                    for (d = 0; d < context->depth; ++d) {
                        context->new_palette[*context->ncolors
                                             * context->depth + d]
                            = context->palette[color_index
                                               * context->depth + d];
                    }
                    if (palette_float != NULL
                            && new_palette_float != NULL
                            && float_depth > 0) {
                        for (float_index = 0;
                                float_index < float_depth;
                                ++float_index) {
                            new_palette_float[*context->ncolors
                                               * float_depth
                                               + float_index]
                                = palette_float[color_index * float_depth
                                                + float_index];
                        }
                    }
                    ++*context->ncolors;
                    context->migration_map[color_index] = *context->ncolors;
                } else {
                    if (absolute_y >= context->output_start) {
                        context->result[pos] =
                            context->migration_map[color_index] - 1;
                    }
                }
            }
            if (absolute_y >= context->output_start) {
                sixel_dither_pipeline_row_notify(dither, absolute_y);
            }
        }
        memcpy(context->palette, context->new_palette,
               (size_t)(*context->ncolors * context->depth));
        if (palette_float != NULL
                && new_palette_float != NULL
                && float_depth > 0) {
            memcpy(palette_float,
                   new_palette_float,
                   (size_t)(*context->ncolors * float_depth)
                       * sizeof(float));
        }
    } else {
        int x;

        for (y = 0; y < context->height; ++y) {
            absolute_y = context->band_origin + y;
            int start;
            int end;
            int step;
            int direction;

            sixel_dither_scanline_params(serpentine, absolute_y,
                                         context->width,
                                         &start, &end, &step, &direction);
            (void)direction;
            for (x = start; x != end; x += step) {
                int pos;
                int d;

                pos = y * context->width + x;
                for (d = 0; d < context->depth; ++d) {
                    float val;

                    val = context->pixels_float[pos * context->depth + d]
                        + f_mask(x, y, d) * jitter_scale;
                    val = sixel_pixelformat_float_channel_clamp(
                        context->pixelformat,
                        d,
                        val);
                    if (need_float_pixel) {
                        lookup_pixel_float[d] = val;
                    }
                    if (!lookup_wants_float && !use_palette_float_lookup) {
                        quantized[d]
                            = sixel_pixelformat_float_channel_to_byte(
                                  context->pixelformat,
                                  d,
                                  val);
                    }
                }
                if (absolute_y >= context->output_start) {
                    if (lookup_wants_float) {
                        lookup_pixel = (unsigned char const *)(void const *)
                            lookup_pixel_float;
                        context->result[pos] = context->lookup(
                            lookup_pixel,
                            context->depth,
                            context->palette,
                            context->reqcolor,
                            context->indextable,
                            context->complexion);
                    } else if (use_palette_float_lookup) {
                        context->result[pos] =
                            sixel_dither_lookup_palette_float32(
                                lookup_pixel_float,
                                context->depth,
                                palette_float,
                                context->reqcolor,
                                context->complexion);
                    } else {
                        lookup_pixel = quantized;
                        context->result[pos] = context->lookup(
                            lookup_pixel,
                            context->depth,
                            context->palette,
                            context->reqcolor,
                            context->indextable,
                            context->complexion);
                    }
                }
            }
            if (absolute_y >= context->output_start) {
                sixel_dither_pipeline_row_notify(dither, absolute_y);
            }
        }
        *context->ncolors = context->reqcolor;
    }

    return SIXEL_OK;
}

/* emacs Local Variables:      */
/* emacs mode: c               */
/* emacs tab-width: 4          */
/* emacs indent-tabs-mode: nil */
/* emacs c-basic-offset: 4     */
/* emacs End:                  */
/* vim: set expandtab ts=4 sts=4 sw=4 : */
/* EOF */

1	/*
2	* SPDX-License-Identifier: MIT
3	*
4	* Copyright (c) 2025 libsixel developers. See `AUTHORS`.
5	*
6	* Permission is hereby granted, free of charge, to any person obtaining a copy
7	* of this software and associated documentation files (the "Software"), to deal
8	* in the Software without restriction, including without limitation the rights
9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10	* copies of the Software, and to permit persons to whom the Software is
11	* furnished to do so, subject to the following conditions:
12	*
13	* The above copyright notice and this permission notice shall be included in
14	* all copies or substantial portions of the Software.
15	*
16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22	* SOFTWARE.
23	*/
24
25	#include "config.h"
26
27	#if HAVE_MATH_H
28	# include <math.h>
29	#endif /* HAVE_MATH_H */
30	#include <string.h>
31
32	#include "dither-positional-float32.h"
33	#include "dither-common-pipeline.h"
34	#include "pixelformat.h"
35
36	static void
37	sixel_dither_scanline_params(int serpentine,	×
38	int index,
39	int limit,
40	int *start,
41	int *end,
42	int *step,
43	int *direction)
44	{
45	if (serpentine && (index & 1)) {	×
46	*start = limit - 1;	×
47	*end = -1;	×
48	*step = -1;	×
49	*direction = -1;	×
50	} else {
51	*start = 0;	×
52	*end = limit;	×
53	*step = 1;	×
54	*direction = 1;	×
55	}
56	}	×
57
58	static float
59	mask_a(int x, int y, int c)	×
60	{
61	return ((((x + c * 67) + y * 236) * 119) & 255) / 128.0f - 1.0f;	×
62	}
63
64	static float
65	mask_x(int x, int y, int c)	×
66	{
67	return ((((x + c * 29) ^ (y * 149)) * 1234) & 511) / 256.0f - 1.0f;	×
68	}
69
70	SIXELSTATUS
71	sixel_dither_apply_positional_float32(sixel_dither_t *dither,	×
72	sixel_dither_context_t *context)
73	{	×
74	#if _MSC_VER
75	enum { max_channels = 4 };
76	#else
77	const int max_channels = 4;	×
78	#endif
79	int serpentine;
80	int y;
81	int absolute_y;
82	float (*f_mask)(int x, int y, int c);
83	float jitter_scale;
84	float *palette_float;
85	float *new_palette_float;
86	int float_depth;
87	int float_index;
88	unsigned char *quantized;
89	float lookup_pixel_float[max_channels];	×
90	unsigned char const *lookup_pixel;
91	int lookup_wants_float;
92	int use_palette_float_lookup;
93	int need_float_pixel;
94
95	palette_float = NULL;	×
96	new_palette_float = NULL;	×
97	float_depth = 0;	×
98	quantized = NULL;	×
99	lookup_wants_float = 0;	×
100
101	if (dither == NULL \|\| context == NULL) {	×
102	return SIXEL_BAD_ARGUMENT;	×
103	}
104	if (context->pixels_float == NULL \|\| context->scratch == NULL) {	×
105	return SIXEL_BAD_ARGUMENT;	×
106	}
107	if (context->palette == NULL \|\| context->result == NULL) {	×
108	return SIXEL_BAD_ARGUMENT;	×
109	}
110
111	switch (context->method_for_diffuse) {	×
112	case SIXEL_DIFFUSE_A_DITHER:	×
113	f_mask = mask_a;	×
114	break;	×
115	case SIXEL_DIFFUSE_X_DITHER:	×
116	default:
117	f_mask = mask_x;	×
118	break;	×
119	}
120
121	serpentine = (context->method_for_scan == SIXEL_SCAN_SERPENTINE);	×
122	jitter_scale = 32.0f / 255.0f;	×
123	palette_float = context->palette_float;	×
124	new_palette_float = context->new_palette_float;	×
125	float_depth = context->float_depth;	×
126	quantized = context->scratch;	×
127	lookup_wants_float = (context->lookup_source_is_float != 0);	×
128	use_palette_float_lookup = 0;	×
129	if (context->prefer_palette_float_lookup != 0	×
130	&& palette_float != NULL	×
131	&& float_depth >= context->depth) {	×
132	use_palette_float_lookup = 1;	×
133	}
134	need_float_pixel = lookup_wants_float \|\| use_palette_float_lookup;	×
135
136	if (context->optimize_palette) {	×
137	int x;
138
139	*context->ncolors = 0;	×
140	memset(context->new_palette, 0x00,	×
141	(size_t)SIXEL_PALETTE_MAX * (size_t)context->depth);	×
142	if (new_palette_float != NULL && float_depth > 0) {	×
143	memset(new_palette_float, 0x00,	×
144	(size_t)SIXEL_PALETTE_MAX
145	* (size_t)float_depth * sizeof(float));	×
146	}
147	memset(context->migration_map, 0x00,	×
148	sizeof(unsigned short) * (size_t)SIXEL_PALETTE_MAX);
149	for (y = 0; y < context->height; ++y) {	×
NEW 150	absolute_y = context->band_origin + y;	×
151	int start;
152	int end;
153	int step;
154	int direction;
155
NEW 156	sixel_dither_scanline_params(serpentine, absolute_y,	×
157	context->width,
158	&start, &end, &step, &direction);
159	(void)direction;
160	for (x = start; x != end; x += step) {	×
161	int pos;
162	int d;
163	int color_index;
164
165	pos = y * context->width + x;	×
166	for (d = 0; d < context->depth; ++d) {	×
167	float val;
168
169	val = context->pixels_float[pos * context->depth + d]	×
170	+ f_mask(x, y, d) * jitter_scale;	×
171	val = sixel_pixelformat_float_channel_clamp(	×
172	context->pixelformat,
173	d,
174	val);
175	if (need_float_pixel) {	×
176	lookup_pixel_float[d] = val;	×
177	}
178	if (!lookup_wants_float && !use_palette_float_lookup) {	×
179	quantized[d]	×
180	= sixel_pixelformat_float_channel_to_byte(	×
181	context->pixelformat,
182	d,
183	val);
184	}
185	}
186	if (lookup_wants_float) {	×
187	lookup_pixel = (unsigned char const )(void const )	×
188	lookup_pixel_float;
189	color_index = context->lookup(lookup_pixel,	×
190	context->depth,
191	context->palette,	×
192	context->reqcolor,
193	context->indextable,
194	context->complexion);
195	} else if (use_palette_float_lookup) {	×
196	color_index = sixel_dither_lookup_palette_float32(	×
197	lookup_pixel_float,
198	context->depth,
199	palette_float,
200	context->reqcolor,
201	context->complexion);
202	} else {
203	lookup_pixel = quantized;	×
204	color_index = context->lookup(lookup_pixel,	×
205	context->depth,
206	context->palette,	×
207	context->reqcolor,
208	context->indextable,
209	context->complexion);
210	}
211	if (context->migration_map[color_index] == 0) {	×
NEW 212	if (absolute_y >= context->output_start) {	×
NEW 213	context->result[pos] = *context->ncolors;	×
214	}
215	for (d = 0; d < context->depth; ++d) {	×
216	context->new_palette[*context->ncolors	×
217	* context->depth + d]	×
218	= context->palette[color_index	×
219	* context->depth + d];	×
220	}
221	if (palette_float != NULL	×
222	&& new_palette_float != NULL	×
223	&& float_depth > 0) {	×
224	for (float_index = 0;	×
225	float_index < float_depth;	×
226	++float_index) {	×
227	new_palette_float[*context->ncolors	×
228	* float_depth	×
229	+ float_index]	×
230	= palette_float[color_index * float_depth	×
231	+ float_index];	×
232	}
233	}
234	++*context->ncolors;	×
235	context->migration_map[color_index] = *context->ncolors;	×
236	} else {
NEW 237	if (absolute_y >= context->output_start) {	×
NEW 238	context->result[pos] =	×
NEW 239	context->migration_map[color_index] - 1;	×
240	}
241	}
242	}
NEW 243	if (absolute_y >= context->output_start) {	×
NEW 244	sixel_dither_pipeline_row_notify(dither, absolute_y);	×
245	}
246	}
247	memcpy(context->palette, context->new_palette,	×
248	(size_t)(context->ncolors context->depth));	×
249	if (palette_float != NULL	×
250	&& new_palette_float != NULL	×
251	&& float_depth > 0) {	×
252	memcpy(palette_float,	×
253	new_palette_float,
254	(size_t)(context->ncolors float_depth)	×
255	* sizeof(float));
256	}
257	} else {
258	int x;
259
260	for (y = 0; y < context->height; ++y) {	×
NEW 261	absolute_y = context->band_origin + y;	×
262	int start;
263	int end;
264	int step;
265	int direction;
266
NEW 267	sixel_dither_scanline_params(serpentine, absolute_y,	×
268	context->width,
269	&start, &end, &step, &direction);
270	(void)direction;
271	for (x = start; x != end; x += step) {	×
272	int pos;
273	int d;
274
275	pos = y * context->width + x;	×
276	for (d = 0; d < context->depth; ++d) {	×
277	float val;
278
279	val = context->pixels_float[pos * context->depth + d]	×
280	+ f_mask(x, y, d) * jitter_scale;	×
281	val = sixel_pixelformat_float_channel_clamp(	×
282	context->pixelformat,
283	d,
284	val);
285	if (need_float_pixel) {	×
286	lookup_pixel_float[d] = val;	×
287	}
288	if (!lookup_wants_float && !use_palette_float_lookup) {	×
289	quantized[d]	×
290	= sixel_pixelformat_float_channel_to_byte(	×
291	context->pixelformat,
292	d,
293	val);
294	}
295	}
NEW 296	if (absolute_y >= context->output_start) {	×
NEW 297	if (lookup_wants_float) {	×
NEW 298	lookup_pixel = (unsigned char const )(void const )	×
299	lookup_pixel_float;
NEW 300	context->result[pos] = context->lookup(	×
301	lookup_pixel,
302	context->depth,
NEW 303	context->palette,	×
304	context->reqcolor,
305	context->indextable,
306	context->complexion);
NEW 307	} else if (use_palette_float_lookup) {	×
NEW 308	context->result[pos] =	×
NEW 309	sixel_dither_lookup_palette_float32(	×
310	lookup_pixel_float,
311	context->depth,
312	palette_float,
313	context->reqcolor,
314	context->complexion);
315	} else {
NEW 316	lookup_pixel = quantized;	×
NEW 317	context->result[pos] = context->lookup(	×
318	lookup_pixel,
319	context->depth,
NEW 320	context->palette,	×
321	context->reqcolor,
322	context->indextable,
323	context->complexion);
324	}
325	}
326	}
NEW 327	if (absolute_y >= context->output_start) {	×
NEW 328	sixel_dither_pipeline_row_notify(dither, absolute_y);	×
329	}
330	}
331	*context->ncolors = context->reqcolor;	×
332	}
333
334	return SIXEL_OK;	×
335	}
336
337	/* emacs Local Variables: */
338	/* emacs mode: c */
339	/* emacs tab-width: 4 */
340	/* emacs indent-tabs-mode: nil */
341	/* emacs c-basic-offset: 4 */
342	/* emacs End: */
343	/* vim: set expandtab ts=4 sts=4 sw=4 : */
344	/* EOF */

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