// Copyright 2012 Google Inc. All Rights Reserved. // // Use of this source code is governed by a BSD-style license // that can be found in the COPYING file in the root of the source // tree. An additional intellectual property rights grant can be found // in the file PATENTS. All contributing project authors may // be found in the AUTHORS file in the root of the source tree. // ----------------------------------------------------------------------------- // // Rescaling functions // // Author: Skal (pascal.massimino@gmail.com) #include #include #include "./rescaler.h" //------------------------------------------------------------------------------ #define RFIX 30 #define MULT_FIX(x, y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX) void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height, uint8_t* const dst, int dst_width, int dst_height, int dst_stride, int num_channels, int x_add, int x_sub, int y_add, int y_sub, int32_t* const work) { wrk->x_expand = (src_width < dst_width); wrk->src_width = src_width; wrk->src_height = src_height; wrk->dst_width = dst_width; wrk->dst_height = dst_height; wrk->dst = dst; wrk->dst_stride = dst_stride; wrk->num_channels = num_channels; // for 'x_expand', we use bilinear interpolation wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add - x_sub; wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub; wrk->y_accum = y_add; wrk->y_add = y_add; wrk->y_sub = y_sub; wrk->fx_scale = (1 << RFIX) / x_sub; wrk->fy_scale = (1 << RFIX) / y_sub; wrk->fxy_scale = wrk->x_expand ? ((int64_t)dst_height << RFIX) / (x_sub * src_height) : ((int64_t)dst_height << RFIX) / (x_add * src_height); wrk->irow = work; wrk->frow = work + num_channels * dst_width; } void WebPRescalerImportRow(WebPRescaler* const wrk, const uint8_t* const src, int channel) { const int x_stride = wrk->num_channels; const int x_out_max = wrk->dst_width * wrk->num_channels; int x_in = channel; int x_out; int accum = 0; if (!wrk->x_expand) { int sum = 0; for (x_out = channel; x_out < x_out_max; x_out += x_stride) { accum += wrk->x_add; for (; accum > 0; accum -= wrk->x_sub) { sum += src[x_in]; x_in += x_stride; } { // Emit next horizontal pixel. const int32_t base = src[x_in]; const int32_t frac = base * (-accum); x_in += x_stride; wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac; // fresh fractional start for next pixel sum = (int)MULT_FIX(frac, wrk->fx_scale); } } } else { // simple bilinear interpolation int left = src[channel], right = src[channel]; for (x_out = channel; x_out < x_out_max; x_out += x_stride) { if (accum < 0) { left = right; x_in += x_stride; right = src[x_in]; accum += wrk->x_add; } wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum; accum -= wrk->x_sub; } } // Accumulate the new row's contribution for (x_out = channel; x_out < x_out_max; x_out += x_stride) { wrk->irow[x_out] += wrk->frow[x_out]; } } uint8_t* WebPRescalerExportRow(WebPRescaler* const wrk) { if (wrk->y_accum <= 0) { int x_out = 0; uint8_t* const dst = wrk->dst; int32_t* const irow = wrk->irow; const int32_t* const frow = wrk->frow; const int yscale = wrk->fy_scale * (-wrk->y_accum); const int x_out_max = wrk->dst_width * wrk->num_channels; #if defined(__mips__) // if wrk->fxy_scale can fit into 32 bits use optimized code, // otherwise use C code if ((wrk->fxy_scale >> 32) == 0) { int temp0, temp1, temp3, temp4, temp5, temp6, temp7, loop_end; const int temp2 = (int)(wrk->fxy_scale); const int temp8 = x_out_max << 2; uint8_t* dst_t = (uint8_t*)dst; int32_t* irow_t = (int32_t*)irow; const int32_t* frow_t = (const int32_t*)frow; __asm__ volatile( "addiu %[temp6], $zero, -256 \n\t" "addiu %[temp7], $zero, 255 \n\t" "li %[temp3], 0x10000 \n\t" "li %[temp4], 0x8000 \n\t" "addu %[loop_end], %[frow_t], %[temp8] \n\t" "1: \n\t" "lw %[temp0], 0(%[frow_t]) \n\t" "mult %[temp3], %[temp4] \n\t" "addiu %[frow_t], %[frow_t], 4 \n\t" "sll %[temp0], %[temp0], 2 \n\t" "madd %[temp0], %[yscale] \n\t" "mfhi %[temp1] \n\t" "lw %[temp0], 0(%[irow_t]) \n\t" "addiu %[dst_t], %[dst_t], 1 \n\t" "addiu %[irow_t], %[irow_t], 4 \n\t" "subu %[temp0], %[temp0], %[temp1] \n\t" "mult %[temp3], %[temp4] \n\t" "sll %[temp0], %[temp0], 2 \n\t" "madd %[temp0], %[temp2] \n\t" "mfhi %[temp5] \n\t" "sw %[temp1], -4(%[irow_t]) \n\t" "and %[temp0], %[temp5], %[temp6] \n\t" "slti %[temp1], %[temp5], 0 \n\t" "beqz %[temp0], 2f \n\t" "xor %[temp5], %[temp5], %[temp5] \n\t" "movz %[temp5], %[temp7], %[temp1] \n\t" "2: \n\t" "sb %[temp5], -1(%[dst_t]) \n\t" "bne %[frow_t], %[loop_end], 1b \n\t" : [temp0]"=&r"(temp0), [temp1]"=&r"(temp1), [temp3]"=&r"(temp3), [temp4]"=&r"(temp4), [temp5]"=&r"(temp5), [temp6]"=&r"(temp6), [temp7]"=&r"(temp7), [frow_t]"+r"(frow_t), [irow_t]"+r"(irow_t), [dst_t]"+r"(dst_t), [loop_end]"=&r"(loop_end) : [temp2]"r"(temp2), [yscale]"r"(yscale), [temp8]"r"(temp8) : "memory", "hi", "lo" ); x_out = x_out_max; } #endif // __mips__ for (; x_out < x_out_max; ++x_out) { const int frac = (int)MULT_FIX(frow[x_out], yscale); const int v = (int)MULT_FIX(irow[x_out] - frac, wrk->fxy_scale); dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255; irow[x_out] = frac; // new fractional start } wrk->y_accum += wrk->y_add; wrk->dst += wrk->dst_stride; return dst; } else { return NULL; } } #undef MULT_FIX #undef RFIX //------------------------------------------------------------------------------ // all-in-one calls int WebPRescaleNeededLines(const WebPRescaler* const wrk, int max_num_lines) { const int num_lines = (wrk->y_accum + wrk->y_sub - 1) / wrk->y_sub; return (num_lines > max_num_lines) ? max_num_lines : num_lines; } int WebPRescalerImport(WebPRescaler* const wrk, int num_lines, const uint8_t* src, int src_stride) { int total_imported = 0; while (total_imported < num_lines && wrk->y_accum > 0) { int channel; for (channel = 0; channel < wrk->num_channels; ++channel) { WebPRescalerImportRow(wrk, src, channel); } src += src_stride; ++total_imported; wrk->y_accum -= wrk->y_sub; } return total_imported; } int WebPRescalerExport(WebPRescaler* const rescaler) { int total_exported = 0; while (WebPRescalerHasPendingOutput(rescaler)) { WebPRescalerExportRow(rescaler); ++total_exported; } return total_exported; } //------------------------------------------------------------------------------