440 lines
12 KiB
C
440 lines
12 KiB
C
/* snes_ntsc 0.2.2. http://www.slack.net/~ant/ */
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/* Common implementation of NTSC filters */
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#include <assert.h>
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#include <math.h>
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/* Copyright (C) 2006 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#define DISABLE_CORRECTION 0
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#undef PI
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#define PI 3.14159265358979323846f
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#ifndef LUMA_CUTOFF
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#define LUMA_CUTOFF 0.20
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#endif
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#ifndef gamma_size
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#define gamma_size 1
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#endif
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#ifndef rgb_bits
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#define rgb_bits 8
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#endif
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#ifndef artifacts_max
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#define artifacts_max (artifacts_mid * 1.5f)
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#endif
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#ifndef fringing_max
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#define fringing_max (fringing_mid * 2)
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#endif
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#ifndef STD_HUE_CONDITION
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#define STD_HUE_CONDITION( setup ) 1
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#endif
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#define ext_decoder_hue (std_decoder_hue + 15)
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#define rgb_unit (1 << rgb_bits)
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#define rgb_offset (rgb_unit * 2 + 0.5f)
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enum { burst_size = snes_ntsc_entry_size / burst_count };
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enum { kernel_half = 16 };
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enum { kernel_size = kernel_half * 2 + 1 };
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typedef struct init_t
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{
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float to_rgb [burst_count * 6];
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float to_float [gamma_size];
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float contrast;
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float brightness;
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float artifacts;
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float fringing;
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float kernel [rescale_out * kernel_size * 2];
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} init_t;
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#define ROTATE_IQ( i, q, sin_b, cos_b ) {\
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float t;\
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t = i * cos_b - q * sin_b;\
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q = i * sin_b + q * cos_b;\
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i = t;\
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}
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static void init_filters( init_t* impl, snes_ntsc_setup_t const* setup )
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{
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#if rescale_out > 1
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float kernels [kernel_size * 2];
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#else
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float* const kernels = impl->kernel;
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#endif
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/* generate luma (y) filter using sinc kernel */
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{
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/* sinc with rolloff (dsf) */
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float const rolloff = 1 + (float) setup->sharpness * (float) 0.032;
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float const maxh = 32;
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float const pow_a_n = (float) pow( rolloff, maxh );
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float sum;
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int i;
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/* quadratic mapping to reduce negative (blurring) range */
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float to_angle = (float) setup->resolution + 1;
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to_angle = PI / maxh * (float) LUMA_CUTOFF * (to_angle * to_angle + 1);
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kernels [kernel_size * 3 / 2] = maxh; /* default center value */
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for ( i = 0; i < kernel_half * 2 + 1; i++ )
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{
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int x = i - kernel_half;
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float angle = x * to_angle;
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/* instability occurs at center point with rolloff very close to 1.0 */
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if ( x || pow_a_n > (float) 1.056 || pow_a_n < (float) 0.981 )
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{
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float rolloff_cos_a = rolloff * (float) cos( angle );
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float num = 1 - rolloff_cos_a -
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pow_a_n * (float) cos( maxh * angle ) +
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pow_a_n * rolloff * (float) cos( (maxh - 1) * angle );
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float den = 1 - rolloff_cos_a - rolloff_cos_a + rolloff * rolloff;
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float dsf = num / den;
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kernels [kernel_size * 3 / 2 - kernel_half + i] = dsf - (float) 0.5;
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}
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}
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/* apply blackman window and find sum */
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sum = 0;
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for ( i = 0; i < kernel_half * 2 + 1; i++ )
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{
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float x = PI * 2 / (kernel_half * 2) * i;
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float blackman = 0.42f - 0.5f * (float) cos( x ) + 0.08f * (float) cos( x * 2 );
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sum += (kernels [kernel_size * 3 / 2 - kernel_half + i] *= blackman);
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}
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/* normalize kernel */
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sum = 1.0f / sum;
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for ( i = 0; i < kernel_half * 2 + 1; i++ )
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{
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int x = kernel_size * 3 / 2 - kernel_half + i;
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kernels [x] *= sum;
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assert( kernels [x] == kernels [x] ); /* catch numerical instability */
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}
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}
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/* generate chroma (iq) filter using gaussian kernel */
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{
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float const cutoff_factor = -0.03125f;
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float cutoff = (float) setup->bleed;
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int i;
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if ( cutoff < 0 )
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{
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/* keep extreme value accessible only near upper end of scale (1.0) */
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cutoff *= cutoff;
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cutoff *= cutoff;
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cutoff *= cutoff;
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cutoff *= -30.0f / 0.65f;
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}
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cutoff = cutoff_factor - 0.65f * cutoff_factor * cutoff;
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for ( i = -kernel_half; i <= kernel_half; i++ )
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kernels [kernel_size / 2 + i] = (float) exp( i * i * cutoff );
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/* normalize even and odd phases separately */
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for ( i = 0; i < 2; i++ )
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{
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float sum = 0;
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int x;
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for ( x = i; x < kernel_size; x += 2 )
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sum += kernels [x];
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sum = 1.0f / sum;
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for ( x = i; x < kernel_size; x += 2 )
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{
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kernels [x] *= sum;
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assert( kernels [x] == kernels [x] ); /* catch numerical instability */
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}
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}
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}
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/*
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printf( "luma:\n" );
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for ( i = kernel_size; i < kernel_size * 2; i++ )
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printf( "%f\n", kernels [i] );
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printf( "chroma:\n" );
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for ( i = 0; i < kernel_size; i++ )
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printf( "%f\n", kernels [i] );
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*/
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/* generate linear rescale kernels */
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#if rescale_out > 1
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{
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float weight = 1.0f;
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float* out = impl->kernel;
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int n = rescale_out;
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do
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{
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float remain = 0;
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int i;
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weight -= 1.0f / rescale_in;
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for ( i = 0; i < kernel_size * 2; i++ )
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{
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float cur = kernels [i];
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float m = cur * weight;
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*out++ = m + remain;
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remain = cur - m;
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}
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}
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while ( --n );
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}
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#endif
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}
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static float const default_decoder [6] =
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{ 0.956f, 0.621f, -0.272f, -0.647f, -1.105f, 1.702f };
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static void init( init_t* impl, snes_ntsc_setup_t const* setup )
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{
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impl->brightness = (float) setup->brightness * (0.5f * rgb_unit) + rgb_offset;
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impl->contrast = (float) setup->contrast * (0.5f * rgb_unit) + rgb_unit;
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#ifdef default_palette_contrast
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if ( !setup->palette )
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impl->contrast *= default_palette_contrast;
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#endif
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impl->artifacts = (float) setup->artifacts;
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if ( impl->artifacts > 0 )
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impl->artifacts *= artifacts_max - artifacts_mid;
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impl->artifacts = impl->artifacts * artifacts_mid + artifacts_mid;
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impl->fringing = (float) setup->fringing;
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if ( impl->fringing > 0 )
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impl->fringing *= fringing_max - fringing_mid;
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impl->fringing = impl->fringing * fringing_mid + fringing_mid;
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init_filters( impl, setup );
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/* generate gamma table */
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if ( gamma_size > 1 )
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{
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float const to_float = 1.0f / (gamma_size - (gamma_size > 1));
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float const gamma = 1.1333f - (float) setup->gamma * 0.5f;
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/* match common PC's 2.2 gamma to TV's 2.65 gamma */
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int i;
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for ( i = 0; i < gamma_size; i++ )
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impl->to_float [i] =
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(float) pow( i * to_float, gamma ) * impl->contrast + impl->brightness;
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}
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/* setup decoder matricies */
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{
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float hue = (float) setup->hue * PI + PI / 180 * ext_decoder_hue;
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float sat = (float) setup->saturation + 1;
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float const* decoder = setup->decoder_matrix;
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if ( !decoder )
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{
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decoder = default_decoder;
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if ( STD_HUE_CONDITION( setup ) )
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hue += PI / 180 * (std_decoder_hue - ext_decoder_hue);
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}
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{
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float s = (float) sin( hue ) * sat;
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float c = (float) cos( hue ) * sat;
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float* out = impl->to_rgb;
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int n;
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n = burst_count;
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do
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{
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float const* in = decoder;
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int n = 3;
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do
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{
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float i = *in++;
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float q = *in++;
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*out++ = i * c - q * s;
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*out++ = i * s + q * c;
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}
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while ( --n );
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if ( burst_count <= 1 )
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break;
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ROTATE_IQ( s, c, 0.866025f, -0.5f ); /* +120 degrees */
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}
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while ( --n );
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}
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}
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}
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/* kernel generation */
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#define RGB_TO_YIQ( r, g, b, y, i ) (\
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(y = (r) * 0.299f + (g) * 0.587f + (b) * 0.114f),\
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(i = (r) * 0.596f - (g) * 0.275f - (b) * 0.321f),\
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((r) * 0.212f - (g) * 0.523f + (b) * 0.311f)\
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)
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#define YIQ_TO_RGB( y, i, q, to_rgb, type, r, g ) (\
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r = (type) (y + to_rgb [0] * i + to_rgb [1] * q),\
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g = (type) (y + to_rgb [2] * i + to_rgb [3] * q),\
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(type) (y + to_rgb [4] * i + to_rgb [5] * q)\
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)
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#define PACK_RGB( r, g, b ) ((r) << 21 | (g) << 11 | (b) << 1)
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enum { rgb_kernel_size = burst_size / alignment_count };
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enum { rgb_bias = rgb_unit * 2 * snes_ntsc_rgb_builder };
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typedef struct pixel_info_t
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{
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int offset;
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float negate;
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float kernel [4];
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} pixel_info_t;
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#if rescale_in > 1
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#define PIXEL_OFFSET_( ntsc, scaled ) \
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(kernel_size / 2 + ntsc + (scaled != 0) + (rescale_out - scaled) % rescale_out + \
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(kernel_size * 2 * scaled))
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#define PIXEL_OFFSET( ntsc, scaled ) \
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PIXEL_OFFSET_( ((ntsc) - (scaled) / rescale_out * rescale_in),\
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(((scaled) + rescale_out * 10) % rescale_out) ),\
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(1.0f - (((ntsc) + 100) & 2))
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#else
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#define PIXEL_OFFSET( ntsc, scaled ) \
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(kernel_size / 2 + (ntsc) - (scaled)),\
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(1.0f - (((ntsc) + 100) & 2))
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#endif
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extern pixel_info_t const snes_ntsc_pixels [alignment_count];
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/* Generate pixel at all burst phases and column alignments */
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static void gen_kernel( init_t* impl, float y, float i, float q, snes_ntsc_rgb_t* out )
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{
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/* generate for each scanline burst phase */
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float const* to_rgb = impl->to_rgb;
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int burst_remain = burst_count;
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y -= rgb_offset;
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do
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{
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/* Encode yiq into *two* composite signals (to allow control over artifacting).
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Convolve these with kernels which: filter respective components, apply
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sharpening, and rescale horizontally. Convert resulting yiq to rgb and pack
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into integer. Based on algorithm by NewRisingSun. */
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pixel_info_t const* pixel = snes_ntsc_pixels;
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int alignment_remain = alignment_count;
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do
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{
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/* negate is -1 when composite starts at odd multiple of 2 */
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float const yy = y * impl->fringing * pixel->negate;
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float const ic0 = (i + yy) * pixel->kernel [0];
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float const qc1 = (q + yy) * pixel->kernel [1];
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float const ic2 = (i - yy) * pixel->kernel [2];
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float const qc3 = (q - yy) * pixel->kernel [3];
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float const factor = impl->artifacts * pixel->negate;
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float const ii = i * factor;
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float const yc0 = (y + ii) * pixel->kernel [0];
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float const yc2 = (y - ii) * pixel->kernel [2];
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float const qq = q * factor;
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float const yc1 = (y + qq) * pixel->kernel [1];
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float const yc3 = (y - qq) * pixel->kernel [3];
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float const* k = &impl->kernel [pixel->offset];
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int n;
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++pixel;
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for ( n = rgb_kernel_size; n; --n )
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{
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float i = k[0]*ic0 + k[2]*ic2;
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float q = k[1]*qc1 + k[3]*qc3;
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float y = k[kernel_size+0]*yc0 + k[kernel_size+1]*yc1 +
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k[kernel_size+2]*yc2 + k[kernel_size+3]*yc3 + rgb_offset;
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if ( rescale_out <= 1 )
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k--;
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else if ( k < &impl->kernel [kernel_size * 2 * (rescale_out - 1)] )
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k += kernel_size * 2 - 1;
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else
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k -= kernel_size * 2 * (rescale_out - 1) + 2;
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{
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int r, g, b = YIQ_TO_RGB( y, i, q, to_rgb, int, r, g );
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*out++ = PACK_RGB( r, g, b ) - rgb_bias;
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}
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}
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}
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while ( alignment_count > 1 && --alignment_remain );
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if ( burst_count <= 1 )
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break;
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to_rgb += 6;
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ROTATE_IQ( i, q, -0.866025f, -0.5f ); /* -120 degrees */
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}
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while ( --burst_remain );
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}
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static void correct_errors( snes_ntsc_rgb_t color, snes_ntsc_rgb_t* out );
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#if DISABLE_CORRECTION
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#define CORRECT_ERROR( a ) { out [i] += rgb_bias; }
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#define DISTRIBUTE_ERROR( a, b, c ) { out [i] += rgb_bias; }
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#else
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#define CORRECT_ERROR( a ) { out [a] += error; }
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#define DISTRIBUTE_ERROR( a, b, c ) {\
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snes_ntsc_rgb_t fourth = (error + 2 * snes_ntsc_rgb_builder) >> 2;\
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fourth &= (rgb_bias >> 1) - snes_ntsc_rgb_builder;\
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fourth -= rgb_bias >> 2;\
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out [a] += fourth;\
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out [b] += fourth;\
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out [c] += fourth;\
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out [i] += error - (fourth * 3);\
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}
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#endif
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#define RGB_PALETTE_OUT( rgb, out_ )\
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{\
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unsigned char* out = (out_);\
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snes_ntsc_rgb_t clamped = (rgb);\
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SNES_NTSC_CLAMP_( clamped, (8 - rgb_bits) );\
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out [0] = (unsigned char) (clamped >> 21);\
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out [1] = (unsigned char) (clamped >> 11);\
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out [2] = (unsigned char) (clamped >> 1);\
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}
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/* blitter related */
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#ifndef restrict
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#if defined (__GNUC__)
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#define restrict __restrict__
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#elif defined (_MSC_VER) && _MSC_VER > 1300
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#define restrict __restrict
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#else
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/* no support for restricted pointers */
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#define restrict
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#endif
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#endif
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#include <limits.h>
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#if SNES_NTSC_OUT_DEPTH <= 16
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#if USHRT_MAX == 0xFFFF
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typedef unsigned short snes_ntsc_out_t;
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#else
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#error "Need 16-bit int type"
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#endif
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#else
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#if UINT_MAX == 0xFFFFFFFF
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typedef unsigned int snes_ntsc_out_t;
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#elif ULONG_MAX == 0xFFFFFFFF
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typedef unsigned long snes_ntsc_out_t;
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#else
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#error "Need 32-bit int type"
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#endif
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#endif
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