mirror of
https://github.com/CTCaer/RetroArch.git
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251 lines
7.3 KiB
C
251 lines
7.3 KiB
C
#include "filter.h"
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#include <math.h>
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#include <stdio.h>
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#include <string.h>
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static bool allocate_filters(struct scaler_ctx *ctx)
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{
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ctx->horiz.filter = (int16_t*)scaler_alloc(sizeof(int16_t), ctx->horiz.filter_stride * ctx->out_width);
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ctx->horiz.filter_pos = (int*)scaler_alloc(sizeof(int), ctx->out_width);
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ctx->vert.filter = (int16_t*)scaler_alloc(sizeof(int16_t), ctx->vert.filter_stride * ctx->out_height);
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ctx->vert.filter_pos = (int*)scaler_alloc(sizeof(int), ctx->out_height);
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return ctx->horiz.filter && ctx->vert.filter;
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}
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static void gen_filter_point_sub(struct scaler_filter *filter, int len, int pos, int step)
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{
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for (int i = 0; i < len; i++, pos += step)
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{
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filter->filter_pos[i] = pos >> 16;
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filter->filter[i] = FILTER_UNITY;
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}
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}
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static bool gen_filter_point(struct scaler_ctx *ctx)
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{
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ctx->horiz.filter_len = 1;
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ctx->horiz.filter_stride = 1;
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ctx->vert.filter_len = 1;
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ctx->vert.filter_stride = 1;
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if (!allocate_filters(ctx))
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return false;
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int x_pos = (1 << 15) * ctx->in_width / ctx->out_width - (1 << 15);
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int x_step = (1 << 16) * ctx->in_width / ctx->out_width;
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int y_pos = (1 << 15) * ctx->in_height / ctx->out_height - (1 << 15);
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int y_step = (1 << 16) * ctx->in_height / ctx->out_height;
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gen_filter_point_sub(&ctx->horiz, ctx->out_width, x_pos, x_step);
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gen_filter_point_sub(&ctx->vert, ctx->out_height, y_pos, y_step);
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return true;
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}
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static void gen_filter_bilinear_sub(struct scaler_filter *filter, int len, int pos, int step)
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{
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for (int i = 0; i < len; i++, pos += step)
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{
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filter->filter_pos[i] = pos >> 16;
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filter->filter[i * 2 + 1] = (pos & 0xffff) >> 2;
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filter->filter[i * 2 + 0] = FILTER_UNITY - filter->filter[i * 2 + 1];
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}
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}
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static bool gen_filter_bilinear(struct scaler_ctx *ctx)
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{
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ctx->horiz.filter_len = 2;
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ctx->horiz.filter_stride = 2;
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ctx->vert.filter_len = 2;
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ctx->vert.filter_stride = 2;
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if (!allocate_filters(ctx))
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return false;
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int x_pos = (1 << 15) * ctx->in_width / ctx->out_width - (1 << 15);
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int x_step = (1 << 16) * ctx->in_width / ctx->out_width;
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int y_pos = (1 << 15) * ctx->in_height / ctx->out_height - (1 << 15);
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int y_step = (1 << 16) * ctx->in_height / ctx->out_height;
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gen_filter_bilinear_sub(&ctx->horiz, ctx->out_width, x_pos, x_step);
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gen_filter_bilinear_sub(&ctx->vert, ctx->out_height, y_pos, y_step);
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return true;
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}
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static inline double sinc(double phase)
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{
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if (fabs(phase) < 0.0001)
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return 1.0;
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else
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return sin(phase) / phase;
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}
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static inline unsigned next_pow2(unsigned v)
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{
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v--;
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v |= v >> 1;
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v |= v >> 2;
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v |= v >> 4;
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v |= v >> 8;
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v |= v >> 16;
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v++;
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return v;
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}
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static void gen_filter_sinc_sub(struct scaler_filter *filter, int len, int pos, int step, double phase_mul)
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{
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const int sinc_size = filter->filter_len;
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for (int i = 0; i < len; i++, pos += step)
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{
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filter->filter_pos[i] = pos >> 16;
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//int16_t sinc_sum = 0;
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for (int j = 0; j < sinc_size; j++)
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{
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double sinc_phase = M_PI * ((double)((sinc_size << 15) + (pos & 0xffff)) / 0x10000 - j);
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double lanczos_phase = sinc_phase / ((sinc_size >> 1));
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int16_t sinc_val = FILTER_UNITY * sinc(sinc_phase * phase_mul) * sinc(lanczos_phase) * phase_mul;
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//sinc_sum += sinc_val;
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filter->filter[i * sinc_size + j] = sinc_val;
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}
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//fprintf(stderr, "Sinc sum = %.3lf\n", (double)sinc_sum / FILTER_UNITY);
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}
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}
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static bool gen_filter_sinc(struct scaler_ctx *ctx)
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{
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// Need to expand the filter when downsampling to get a proper low-pass effect.
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const int sinc_size = 8 * (ctx->in_width > ctx->out_width ? next_pow2(ctx->in_width / ctx->out_width) : 1);
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ctx->horiz.filter_len = sinc_size;
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ctx->horiz.filter_stride = sinc_size;
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ctx->vert.filter_len = sinc_size;
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ctx->vert.filter_stride = sinc_size;
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if (!allocate_filters(ctx))
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return false;
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int x_pos = (1 << 15) * ctx->in_width / ctx->out_width - (1 << 15) - (sinc_size << 15);
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int x_step = (1 << 16) * ctx->in_width / ctx->out_width;
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int y_pos = (1 << 15) * ctx->in_height / ctx->out_height - (1 << 15) - (sinc_size << 15);
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int y_step = (1 << 16) * ctx->in_height / ctx->out_height;
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double phase_mul_horiz = ctx->in_width > ctx->out_width ? (double)ctx->out_width / ctx->in_width : 1.0;
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double phase_mul_vert = ctx->in_height > ctx->out_height ? (double)ctx->out_height / ctx->in_height : 1.0;
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gen_filter_sinc_sub(&ctx->horiz, ctx->out_width, x_pos, x_step, phase_mul_horiz);
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gen_filter_sinc_sub(&ctx->vert, ctx->out_height, y_pos, y_step, phase_mul_vert);
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return true;
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}
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static bool validate_filter(struct scaler_ctx *ctx)
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{
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int max_w_pos = ctx->in_width - ctx->horiz.filter_len;
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for (int i = 0; i < ctx->out_width; i++)
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{
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if (ctx->horiz.filter_pos[i] > max_w_pos || ctx->horiz.filter_pos[i] < 0)
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{
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fprintf(stderr, "Out X = %d => In X = %d\n", i, ctx->horiz.filter_pos[i]);
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return false;
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}
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}
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int max_h_pos = ctx->in_height - ctx->vert.filter_len;
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for (int i = 0; i < ctx->out_height; i++)
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{
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if (ctx->vert.filter_pos[i] > max_h_pos || ctx->vert.filter_pos[i] < 0)
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{
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fprintf(stderr, "Out Y = %d => In Y = %d\n", i, ctx->vert.filter_pos[i]);
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return false;
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}
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}
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return true;
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}
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static void fixup_filter_sub(struct scaler_filter *filter, int out_len, int in_len)
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{
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int max_pos = in_len - filter->filter_len;
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for (int i = 0; i < out_len; i++)
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{
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int postsample = filter->filter_pos[i] - max_pos;
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int presample = -filter->filter_pos[i];
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if (postsample > 0)
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{
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filter->filter_pos[i] -= postsample;
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int16_t *base_filter = filter->filter + i * filter->filter_stride;
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if (postsample > (int)filter->filter_len)
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memset(base_filter, 0, filter->filter_len * sizeof(int16_t));
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else
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{
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memmove(base_filter + postsample, base_filter, (filter->filter_len - postsample) * sizeof(int16_t));
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memset(base_filter, 0, postsample * sizeof(int16_t));
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}
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}
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if (presample > 0)
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{
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filter->filter_pos[i] += presample;
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int16_t *base_filter = filter->filter + i * filter->filter_stride;
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if (presample > (int)filter->filter_len)
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memset(base_filter, 0, filter->filter_len * sizeof(int16_t));
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else
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{
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memmove(base_filter, base_filter + presample, (filter->filter_len - presample) * sizeof(int16_t));
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memset(base_filter + (filter->filter_len - presample), 0, presample * sizeof(int16_t));
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}
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}
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}
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}
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// Makes sure that we never sample outside our rectangle.
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static void fixup_filter(struct scaler_ctx *ctx)
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{
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fixup_filter_sub(&ctx->horiz, ctx->out_width, ctx->in_width);
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fixup_filter_sub(&ctx->vert, ctx->out_height, ctx->in_height);
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}
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bool scaler_gen_filter(struct scaler_ctx *ctx)
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{
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bool ret = true;
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switch (ctx->scaler_type)
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{
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case SCALER_TYPE_POINT:
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ret = gen_filter_point(ctx);
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break;
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case SCALER_TYPE_BILINEAR:
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ret = gen_filter_bilinear(ctx);
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break;
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case SCALER_TYPE_SINC:
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ret = gen_filter_sinc(ctx);
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break;
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default:
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return false;
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}
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if (!ret)
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return false;
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fixup_filter(ctx);
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return validate_filter(ctx);
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}
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