From e6877671f1b4f4f382f211720c9b648eb9b86c50 Mon Sep 17 00:00:00 2001 From: Glenn Randers-Pehrson Date: Sat, 30 May 2015 11:54:45 -0500 Subject: [PATCH] [libpng16] Backported filter selection code from libpng-1.7.0beta51, to combine sub_row, up_row, avg_row, and paeth_row into try_row and tst_row. --- ANNOUNCE | 9 +- CHANGES | 4 +- pngstruct.h | 16 +- pngwrite.c | 124 +++++---- pngwutil.c | 714 ++++++++++++++++++++++++---------------------------- 5 files changed, 403 insertions(+), 464 deletions(-) diff --git a/ANNOUNCE b/ANNOUNCE index 8aa699f09..b9a22623a 100644 --- a/ANNOUNCE +++ b/ANNOUNCE @@ -1,4 +1,4 @@ -Libpng 1.6.18beta05 - May 29, 2015 +Libpng 1.6.18beta05 - May 30, 2015 This is not intended to be a public release. It will be replaced within a few weeks by a public version or by another test version. @@ -51,9 +51,12 @@ Version 1.6.18beta04 [May 20, 2015] type and can be defined on the command line, allowing testing in beta builds (John Bowler). Avoid Coverity issue 80858 (REVERSE NULL) in pngtest.c - Avoid a harmless potential integer overflow in png_XYZ_from_xy(). + Avoid a harmless potential integer overflow in png_XYZ_from_xy() (Bug + report from Christopher Ferris). -Version 1.6.18beta05 [May 29, 2015] +Version 1.6.18beta05 [May 30, 2015] + Backport filter selection code from libpng-1.7.0beta51, to combine + sub_row, up_row, avg_row, and paeth_row into try_row and tst_row. Send comments/corrections/commendations to png-mng-implement at lists.sf.net (subscription required; visit diff --git a/CHANGES b/CHANGES index a9ed05e56..11786b391 100644 --- a/CHANGES +++ b/CHANGES @@ -5239,7 +5239,9 @@ Version 1.6.18beta04 [May 20, 2015] Avoid a harmless potential integer overflow in png_XYZ_from_xy() (Bug report from Christopher Ferris). -Version 1.6.18beta05 [May 29, 2015] +Version 1.6.18beta05 [May 30, 2015] + Backport filter selection code from libpng-1.7.0beta51, to combine + sub_row, up_row, avg_row, and paeth_row into try_row and tst_row. Send comments/corrections/commendations to png-mng-implement at lists.sf.net (subscription required; visit diff --git a/pngstruct.h b/pngstruct.h index 8420d0997..4d34ac05b 100644 --- a/pngstruct.h +++ b/pngstruct.h @@ -219,16 +219,18 @@ struct png_struct_def png_uint_32 row_number; /* current row in interlace pass */ png_uint_32 chunk_name; /* PNG_CHUNK() id of current chunk */ png_bytep prev_row; /* buffer to save previous (unfiltered) row. - * This is a pointer into big_prev_row + * While reading this is a pointer into + * big_prev_row; while writing it is separately + * allocated if needed. */ png_bytep row_buf; /* buffer to save current (unfiltered) row. - * This is a pointer into big_row_buf + * While reading, this is a pointer into + * big_row_buf; while writing it is separately + * allocated. */ -#ifdef PNG_WRITE_SUPPORTED - png_bytep sub_row; /* buffer to save "sub" row when filtering */ - png_bytep up_row; /* buffer to save "up" row when filtering */ - png_bytep avg_row; /* buffer to save "avg" row when filtering */ - png_bytep paeth_row; /* buffer to save "Paeth" row when filtering */ +#ifdef PNG_WRITE_FILTER_SUPPORTED + png_bytep try_row; /* buffer to save trial row when filtering */ + png_bytep tst_row; /* buffer to save best trial row when filtering */ #endif png_size_t info_rowbytes; /* Added in 1.5.4: cache of updated row bytes */ diff --git a/pngwrite.c b/pngwrite.c index 305e2df78..18dc19678 100644 --- a/pngwrite.c +++ b/pngwrite.c @@ -942,15 +942,11 @@ png_write_destroy(png_structrp png_ptr) png_ptr->row_buf = NULL; #ifdef PNG_WRITE_FILTER_SUPPORTED png_free(png_ptr, png_ptr->prev_row); - png_free(png_ptr, png_ptr->sub_row); - png_free(png_ptr, png_ptr->up_row); - png_free(png_ptr, png_ptr->avg_row); - png_free(png_ptr, png_ptr->paeth_row); + png_free(png_ptr, png_ptr->try_row); + png_free(png_ptr, png_ptr->tst_row); png_ptr->prev_row = NULL; - png_ptr->sub_row = NULL; - png_ptr->up_row = NULL; - png_ptr->avg_row = NULL; - png_ptr->paeth_row = NULL; + png_ptr->try_row = NULL; + png_ptr->tst_row = NULL; #endif #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED @@ -1057,75 +1053,67 @@ png_set_filter(png_structrp png_ptr, int method, int filters) * wants to start and stop using particular filters during compression, * it should start out with all of the filters, and then remove them * or add them back after the start of compression. + * + * NOTE: this is a nasty constraint on the code, because it means that the + * prev_row buffer must be maintained even if there are currently no + * 'prev_row' requiring filters active. */ if (png_ptr->row_buf != NULL) { -#ifdef PNG_WRITE_FILTER_SUPPORTED - if ((png_ptr->do_filter & PNG_FILTER_SUB) != 0 && - png_ptr->sub_row == NULL) + int num_filters; + png_alloc_size_t buf_size; + + /* Repeat the checks in png_write_start_row; 1 pixel high or wide + * images cannot benefit from certain filters. If this isn't done here + * the check below will fire on 1 pixel high images. + */ + if (png_ptr->height == 1) + filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if (png_ptr->width == 1) + filters &= ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if ((filters & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0 + && png_ptr->prev_row == NULL) { - png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, - (png_ptr->rowbytes + 1)); - png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB; + /* This is the error case, however it is benign - the previous row + * is not available so the filter can't be used. Just warn here. + */ + png_app_warning(png_ptr, + "png_set_filter: UP/AVG/PAETH cannot be added after start"); + filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); } - if ((png_ptr->do_filter & PNG_FILTER_UP) != 0 && - png_ptr->up_row == NULL) + num_filters = 0; + + if (filters & PNG_FILTER_SUB) + num_filters++; + + if (filters & PNG_FILTER_UP) + num_filters++; + + if (filters & PNG_FILTER_AVG) + num_filters++; + + if (filters & PNG_FILTER_PAETH) + num_filters++; + + /* Allocate needed row buffers if they have not already been + * allocated. + */ + buf_size = PNG_ROWBYTES(png_ptr->usr_channels * png_ptr->usr_bit_depth, + png_ptr->width) + 1; + + if (png_ptr->try_row == NULL) + png_ptr->try_row = png_malloc(png_ptr, buf_size); + + if (num_filters > 1) { - if (png_ptr->prev_row == NULL) - { - png_warning(png_ptr, "Can't add Up filter after starting"); - png_ptr->do_filter = (png_byte)(png_ptr->do_filter & - ~PNG_FILTER_UP); - } - - else - { - png_ptr->up_row = (png_bytep)png_malloc(png_ptr, - (png_ptr->rowbytes + 1)); - png_ptr->up_row[0] = PNG_FILTER_VALUE_UP; - } + if (png_ptr->tst_row == NULL) + png_ptr->tst_row = png_malloc(png_ptr, buf_size); } - - if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0 && - png_ptr->avg_row == NULL) - { - if (png_ptr->prev_row == NULL) - { - png_warning(png_ptr, "Can't add Average filter after starting"); - png_ptr->do_filter = (png_byte)(png_ptr->do_filter & - ~PNG_FILTER_AVG); - } - - else - { - png_ptr->avg_row = (png_bytep)png_malloc(png_ptr, - (png_ptr->rowbytes + 1)); - png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG; - } - } - - if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0 && - png_ptr->paeth_row == NULL) - { - if (png_ptr->prev_row == NULL) - { - png_warning(png_ptr, "Can't add Paeth filter after starting"); - png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH); - } - - else - { - png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr, - (png_ptr->rowbytes + 1)); - png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH; - } - } - - if (png_ptr->do_filter == PNG_NO_FILTERS) -#endif /* WRITE_FILTER */ - png_ptr->do_filter = PNG_FILTER_NONE; } + png_ptr->do_filter = (png_byte)filters; } else png_error(png_ptr, "Unknown custom filter method"); diff --git a/pngwutil.c b/pngwutil.c index fd7b5a8b6..d83e37f51 100644 --- a/pngwutil.c +++ b/pngwutil.c @@ -1961,6 +1961,10 @@ png_write_start_row(png_structrp png_ptr) png_alloc_size_t buf_size; int usr_pixel_depth; +#ifdef PNG_WRITE_FILTER_SUPPORTED + int filters; +#endif + png_debug(1, "in png_write_start_row"); usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth; @@ -1971,50 +1975,53 @@ png_write_start_row(png_structrp png_ptr) png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth; /* Set up row buffer */ - png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size); + png_ptr->row_buf = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE; #ifdef PNG_WRITE_FILTER_SUPPORTED - /* Set up filtering buffer, if using this filter */ - if (png_ptr->do_filter & PNG_FILTER_SUB) - { - png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1); + filters = png_ptr->do_filter; - png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB; + if (png_ptr->height == 1) + filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if (png_ptr->width == 1) + filters &= ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if (filters == 0) + filters = PNG_FILTER_NONE; + + png_ptr->do_filter = filters; + + if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG | + PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL) + { + int num_filters = 0; + + png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); + + if (filters & PNG_FILTER_SUB) + num_filters++; + + if (filters & PNG_FILTER_UP) + num_filters++; + + if (filters & PNG_FILTER_AVG) + num_filters++; + + if (filters & PNG_FILTER_PAETH) + num_filters++; + + if (num_filters > 1) + png_ptr->tst_row = png_voidcast(png_bytep, png_malloc(png_ptr, + buf_size)); } - /* We only need to keep the previous row if we are using one of these. */ - if ((png_ptr->do_filter & - (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0) - { - /* Set up previous row buffer */ - png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size); - - if ((png_ptr->do_filter & PNG_FILTER_UP) != 0) - { - png_ptr->up_row = (png_bytep)png_malloc(png_ptr, - png_ptr->rowbytes + 1); - - png_ptr->up_row[0] = PNG_FILTER_VALUE_UP; - } - - if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0) - { - png_ptr->avg_row = (png_bytep)png_malloc(png_ptr, - png_ptr->rowbytes + 1); - - png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG; - } - - if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0) - { - png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr, - png_ptr->rowbytes + 1); - - png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH; - } - } + /* We only need to keep the previous row if we are using one of the following + * filters. + */ + if ((filters & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0) + png_ptr->prev_row = png_calloc(png_ptr, buf_size); #endif /* WRITE_FILTER */ #ifdef PNG_WRITE_INTERLACING_SUPPORTED @@ -2310,6 +2317,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) } #endif + /* This filters the row, chooses which filter to use, if it has not already * been specified by the application, and then writes the row out with the * chosen filter. @@ -2318,42 +2326,232 @@ static void /* PRIVATE */ png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, png_size_t row_bytes); +#ifdef PNG_WRITE_FILTER_SUPPORTED +static png_size_t /* PRIVATE */ +png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, lp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp; + i++, rp++, dp++) + { + v = *dp = *rp; + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1; i < row_bytes; + i++, rp++, lp++, dp++) + { + v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff); + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes, + const png_size_t lmins) +{ + png_bytep rp, dp, pp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < row_bytes; + i++, rp++, pp++, dp++) + { + v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, pp, lp; + png_uint_32 i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < bpp; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); + + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1; i < row_bytes; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) + & 0xff); + + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, pp, cp, lp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < bpp; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); + + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; + i++) + { + int a, b, c, pa, pb, pc, p; + + b = *pp++; + c = *cp++; + a = *lp++; + + p = b - c; + pc = a - c; + +#ifdef PNG_USE_ABS + pa = abs(p); + pb = abs(pc); + pc = abs(p + pc); +#else + pa = p < 0 ? -p : p; + pb = pc < 0 ? -pc : pc; + pc = (p + pc) < 0 ? -(p + pc) : p + pc; +#endif + + p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; + + v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); + + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + + +#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED + #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1) #define PNG_HISHIFT 10 #define PNG_LOMASK ((png_uint_32)0xffffL) #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT)) + +static png_size_t /* PRIVATE */ +png_increase_lmins(png_structrp png_ptr, png_size_t lmins) +{ + /* We temporarily increase the "minimum sum" by the factor we + * would reduce the sum of this filter, so that we can do the + * early exit comparison without scaling the sum each time. + */ + int j; + png_uint_32 lmhi, lmlo; + lmlo = lmins & PNG_LOMASK; + lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; + + for (j = 0; j < png_ptr->num_prev_filters; j++) + { + if (png_ptr->prev_filters[j] == png_ptr->try_row[0]) + { + lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> + PNG_WEIGHT_SHIFT; + + lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> + PNG_WEIGHT_SHIFT; + } + } + + lmlo = (lmlo * png_ptr->inv_filter_costs[png_ptr->try_row[0]]) >> + PNG_COST_SHIFT; + + lmhi = (lmhi * png_ptr->inv_filter_costs[png_ptr->try_row[0]]) >> + PNG_COST_SHIFT; + + if (lmhi > PNG_HIMASK) + lmins = PNG_MAXSUM; + + else + lmins = (lmhi << PNG_HISHIFT) + lmlo; + + return (lmins); +} +#endif /* WRITE_WEIGHTED_FILTER */ + +#endif /* WRITE_FILTER */ + void /* PRIVATE */ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) { - png_bytep best_row; -#ifdef PNG_WRITE_FILTER_SUPPORTED - png_bytep prev_row, row_buf; - png_uint_32 mins, bpp; +#ifndef PNG_WRITE_FILTER_SUPPORTED + png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1); +#else png_byte filter_to_do = png_ptr->do_filter; - png_size_t row_bytes = row_info->rowbytes; + png_bytep row_buf; + png_bytep best_row; + png_uint_32 bpp; #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED int num_p_filters = png_ptr->num_prev_filters; #endif + png_size_t mins; + png_size_t row_bytes = row_info->rowbytes; png_debug(1, "in png_write_find_filter"); #ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED - if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS) - { + if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS) + { /* These will never be selected so we need not test them. */ filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH); - } + } #endif /* Find out how many bytes offset each pixel is */ bpp = (row_info->pixel_depth + 7) >> 3; - prev_row = png_ptr->prev_row; -#endif - best_row = png_ptr->row_buf; -#ifdef PNG_WRITE_FILTER_SUPPORTED - row_buf = best_row; - mins = PNG_MAXSUM; + row_buf = png_ptr->row_buf; + mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the + running sum */; /* The prediction method we use is to find which method provides the * smallest value when summing the absolute values of the distances @@ -2383,19 +2581,16 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) /* We don't need to test the 'no filter' case if this is the only filter * that has been chosen, as it doesn't actually do anything to the data. */ + best_row = png_ptr->row_buf; + + if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE) { png_bytep rp; - png_uint_32 sum = 0; + png_size_t sum = 0; png_size_t i; int v; - for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) - { - v = *rp; - sum += (v < 128) ? v : 256 - v; - } - #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { @@ -2434,6 +2629,28 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) sum = (sumhi << PNG_HISHIFT) + sumlo; } #endif + + if (PNG_SIZE_MAX/128 <= row_bytes) + { + for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) + { + /* Check for overflow */ + if (sum > PNG_SIZE_MAX/128 - 256) + break; + + v = *rp; + sum += (v < 128) ? v : 256 - v; + } + } + else /* Overflow is not possible */ + { + for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) + { + v = *rp; + sum += (v < 128) ? v : 256 - v; + } + } + mins = sum; } @@ -2441,87 +2658,21 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) if (filter_to_do == PNG_FILTER_SUB) /* It's the only filter so no testing is needed */ { - png_bytep rp, lp, dp; - png_size_t i; - - for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp; - i++, rp++, dp++) - { - *dp = *rp; - } - - for (lp = row_buf + 1; i < row_bytes; - i++, rp++, lp++, dp++) - { - *dp = (png_byte)((int)*rp - (int)*lp); - } - - best_row = png_ptr->sub_row; + (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; } else if ((filter_to_do & PNG_FILTER_SUB) != 0) { - png_bytep rp, dp, lp; - png_uint_32 sum = 0, lmins = mins; - png_size_t i; - int v; - + png_size_t sum; + png_size_t lmins = mins; #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED - /* We temporarily increase the "minimum sum" by the factor we - * would reduce the sum of this filter, so that we can do the - * early exit comparison without scaling the sum each time. - */ + png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB; if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) - { - int j; - png_uint_32 lmhi, lmlo; - lmlo = lmins & PNG_LOMASK; - lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - - for (j = 0; j < num_p_filters; j++) - { - if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB) - { - lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - } - } - - lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> - PNG_COST_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> - PNG_COST_SHIFT; - - if (lmhi > PNG_HIMASK) - lmins = PNG_MAXSUM; - - else - lmins = (lmhi << PNG_HISHIFT) + lmlo; - } + lmins = png_increase_lmins(png_ptr, lmins); #endif - for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp; - i++, rp++, dp++) - { - v = *dp = *rp; - - sum += (v < 128) ? v : 256 - v; - } - - for (lp = row_buf + 1; i < row_bytes; - i++, rp++, lp++, dp++) - { - v = *dp = (png_byte)((int)*rp - (int)*lp); - - sum += (v < 128) ? v : 256 - v; - - if (sum > lmins) /* We are already worse, don't continue. */ - break; - } + sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins); #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) @@ -2560,78 +2711,33 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) if (sum < mins) { mins = sum; - best_row = png_ptr->sub_row; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } } } /* Up filter */ if (filter_to_do == PNG_FILTER_UP) { - png_bytep rp, dp, pp; - png_size_t i; - - for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, - pp = prev_row + 1; i < row_bytes; - i++, rp++, pp++, dp++) - { - *dp = (png_byte)((int)*rp - (int)*pp); - } - - best_row = png_ptr->up_row; + (void) png_setup_up_row(png_ptr, row_bytes, mins); + best_row = png_ptr->try_row; } else if ((filter_to_do & PNG_FILTER_UP) != 0) { - png_bytep rp, dp, pp; - png_uint_32 sum = 0, lmins = mins; - png_size_t i; - int v; - - + png_size_t sum; + png_size_t lmins = mins; #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED + png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) - { - int j; - png_uint_32 lmhi, lmlo; - lmlo = lmins & PNG_LOMASK; - lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - - for (j = 0; j < num_p_filters; j++) - { - if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP) - { - lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - } - } - - lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >> - PNG_COST_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >> - PNG_COST_SHIFT; - - if (lmhi > PNG_HIMASK) - lmins = PNG_MAXSUM; - - else - lmins = (lmhi << PNG_HISHIFT) + lmlo; - } + lmins = png_increase_lmins(png_ptr, lmins); #endif - for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, - pp = prev_row + 1; i < row_bytes; i++) - { - v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++); - - sum += (v < 128) ? v : 256 - v; - - if (sum > lmins) /* We are already worse, don't continue. */ - break; - } + sum = png_setup_up_row(png_ptr, row_bytes, lmins); #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) @@ -2670,89 +2776,33 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) if (sum < mins) { mins = sum; - best_row = png_ptr->up_row; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } } } /* Avg filter */ if (filter_to_do == PNG_FILTER_AVG) { - png_bytep rp, dp, pp, lp; - png_uint_32 i; - - for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, - pp = prev_row + 1; i < bpp; i++) - { - *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2)); - } - - for (lp = row_buf + 1; i < row_bytes; i++) - { - *dp++ = - (png_byte)((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)); - } - best_row = png_ptr->avg_row; + (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; } else if ((filter_to_do & PNG_FILTER_AVG) != 0) { - png_bytep rp, dp, pp, lp; - png_uint_32 sum = 0, lmins = mins; - png_size_t i; - int v; - + png_size_t sum; + png_size_t lmins = mins; #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED + png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) - { - int j; - png_uint_32 lmhi, lmlo; - lmlo = lmins & PNG_LOMASK; - lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - - for (j = 0; j < num_p_filters; j++) - { - if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG) - { - lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - } - } - - lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >> - PNG_COST_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >> - PNG_COST_SHIFT; - - if (lmhi > PNG_HIMASK) - lmins = PNG_MAXSUM; - - else - lmins = (lmhi << PNG_HISHIFT) + lmlo; - } + lmins = png_increase_lmins(png_ptr, lmins); #endif - for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, - pp = prev_row + 1; i < bpp; i++) - { - v = *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2)); - - sum += (v < 128) ? v : 256 - v; - } - - for (lp = row_buf + 1; i < row_bytes; i++) - { - v = *dp++ = - (png_byte)(((int)*rp++ - ((int)*pp++ + (int)*lp++) / 2)); - - sum += (v < 128) ? v : 256 - v; - - if (sum > lmins) /* We are already worse, don't continue. */ - break; - } + sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins); #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) @@ -2791,143 +2841,33 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) if (sum < mins) { mins = sum; - best_row = png_ptr->avg_row; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } } } /* Paeth filter */ if ((filter_to_do == PNG_FILTER_PAETH) != 0) { - png_bytep rp, dp, pp, cp, lp; - png_size_t i; - - for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, - pp = prev_row + 1; i < bpp; i++) - { - *dp++ = (png_byte)((int)*rp++ - (int)*pp++); - } - - for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++) - { - int a, b, c, pa, pb, pc, p; - - b = *pp++; - c = *cp++; - a = *lp++; - - p = b - c; - pc = a - c; - -#ifdef PNG_USE_ABS - pa = abs(p); - pb = abs(pc); - pc = abs(p + pc); -#else - pa = p < 0 ? -p : p; - pb = pc < 0 ? -pc : pc; - pc = (p + pc) < 0 ? -(p + pc) : p + pc; -#endif - - p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; - - *dp++ = (png_byte)((int)*rp++ - p); - } - best_row = png_ptr->paeth_row; + (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; } else if ((filter_to_do & PNG_FILTER_PAETH) != 0) { - png_bytep rp, dp, pp, cp, lp; - png_uint_32 sum = 0, lmins = mins; - png_size_t i; - int v; - + png_size_t sum; + png_size_t lmins = mins; #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED + png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) - { - int j; - png_uint_32 lmhi, lmlo; - lmlo = lmins & PNG_LOMASK; - lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - - for (j = 0; j < num_p_filters; j++) - { - if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH) - { - lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> - PNG_WEIGHT_SHIFT; - } - } - - lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >> - PNG_COST_SHIFT; - - lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >> - PNG_COST_SHIFT; - - if (lmhi > PNG_HIMASK) - lmins = PNG_MAXSUM; - - else - lmins = (lmhi << PNG_HISHIFT) + lmlo; - } + lmins = png_increase_lmins(png_ptr, lmins); #endif - for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, - pp = prev_row + 1; i < bpp; i++) - { - v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++); - - sum += (v < 128) ? v : 256 - v; - } - - for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++) - { - int a, b, c, pa, pb, pc, p; - - b = *pp++; - c = *cp++; - a = *lp++; - -#ifndef PNG_SLOW_PAETH - p = b - c; - pc = a - c; -#ifdef PNG_USE_ABS - pa = abs(p); - pb = abs(pc); - pc = abs(p + pc); -#else - pa = p < 0 ? -p : p; - pb = pc < 0 ? -pc : pc; - pc = (p + pc) < 0 ? -(p + pc) : p + pc; -#endif - p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; -#else /* SLOW_PAETH */ - p = a + b - c; - pa = abs(p - a); - pb = abs(p - b); - pc = abs(p - c); - - if (pa <= pb && pa <= pc) - p = a; - - else if (pb <= pc) - p = b; - - else - p = c; -#endif /* SLOW_PAETH */ - - v = *dp++ = (png_byte)((int)*rp++ - p); - - sum += (v < 128) ? v : 256 - v; - - if (sum > lmins) /* We are already worse, don't continue. */ - break; - } + sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins); #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) @@ -2965,15 +2905,19 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) if (sum < mins) { - best_row = png_ptr->paeth_row; + mins = sum; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } } } -#endif /* WRITE_FILTER */ /* Do the actual writing of the filtered row data from the chosen filter. */ png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1); -#ifdef PNG_WRITE_FILTER_SUPPORTED #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* Save the type of filter we picked this time for future calculations */ if (png_ptr->num_prev_filters > 0) @@ -2987,7 +2931,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) png_ptr->prev_filters[j] = best_row[0]; } -#endif +#endif /* WRITE_WEIGHTED_FILTER */ #endif /* WRITE_FILTER */ }