snes_ntsc_impl.h

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/* snes_ntsc 0.2.2. http://www.slack.net/~ant/ */
#ifndef __BLARGG_SNES_NTSC_IMPLEMENTATION_H
#define __BLARGG_SNES_NTSC_IMPLEMENTATION_H

/* Common implementation of NTSC filters */

#include <retro_assert.h>
#include <math.h>

/* Copyright (C) 2006 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details. You should have received a copy of the GNU Lesser General Public
License along with this module; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */

#define DISABLE_CORRECTION 0

#undef PI
#define PI 3.14159265358979323846f

#ifndef LUMA_CUTOFF
    #define LUMA_CUTOFF 0.20
#endif
#ifndef gamma_size
    #define gamma_size 1
#endif
#ifndef rgb_bits
    #define rgb_bits 8
#endif
#ifndef artifacts_max
    #define artifacts_max (artifacts_mid * 1.5f)
#endif
#ifndef fringing_max
    #define fringing_max (fringing_mid * 2)
#endif
#ifndef STD_HUE_CONDITION
    #define STD_HUE_CONDITION( setup ) 1
#endif

#define ext_decoder_hue     (std_decoder_hue + 15)
#define rgb_unit            (1 << rgb_bits)
#define rgb_offset          (rgb_unit * 2 + 0.5f)

enum { burst_size  = snes_ntsc_entry_size / burst_count };
enum { kernel_half = 16 };
enum { kernel_size = kernel_half * 2 + 1 };

typedef struct init_t
{
    float to_rgb [burst_count * 6];
    float to_float [gamma_size];
    float contrast;
    float brightness;
    float artifacts;
    float fringing;
    float kernel [rescale_out * kernel_size * 2];
} init_t;

#define ROTATE_IQ( i, q, sin_b, cos_b ) {\
    float t;\
    t = i * cos_b - q * sin_b;\
    q = i * sin_b + q * cos_b;\
    i = t;\
}

static void init_filters( init_t* impl, snes_ntsc_setup_t const* setup )
{
#if rescale_out > 1
    float kernels [kernel_size * 2];
#else
    float* const kernels = impl->kernel;
#endif

    /* generate luma (y) filter using sinc kernel */
    {
        /* sinc with rolloff (dsf) */
        float const rolloff = 1 + (float) setup->sharpness * (float) 0.032;
        float const maxh = 32;
        float const pow_a_n = (float) pow( rolloff, maxh );
        float sum;
        int i;
        /* quadratic mapping to reduce negative (blurring) range */
        float to_angle = (float) setup->resolution + 1;
        to_angle = PI / maxh * (float) LUMA_CUTOFF * (to_angle * to_angle + 1);

        kernels [kernel_size * 3 / 2] = maxh; /* default center value */
        for ( i = 0; i < kernel_half * 2 + 1; i++ )
        {
            int x = i - kernel_half;
            float angle = x * to_angle;
            /* instability occurs at center point with rolloff very close to 1.0 */
            if ( x || pow_a_n > (float) 1.056 || pow_a_n < (float) 0.981 )
            {
                float rolloff_cos_a = rolloff * (float) cos( angle );
                float num = 1 - rolloff_cos_a -
                        pow_a_n * (float) cos( maxh * angle ) +
                        pow_a_n * rolloff * (float) cos( (maxh - 1) * angle );
                float den = 1 - rolloff_cos_a - rolloff_cos_a + rolloff * rolloff;
                float dsf = num / den;
                kernels [kernel_size * 3 / 2 - kernel_half + i] = dsf - (float) 0.5;
            }
        }

        /* apply blackman window and find sum */
        sum = 0;
        for ( i = 0; i < kernel_half * 2 + 1; i++ )
        {
            float x = PI * 2 / (kernel_half * 2) * i;
            float blackman = 0.42f - 0.5f * (float) cos( x ) + 0.08f * (float) cos( x * 2 );
            sum += (kernels [kernel_size * 3 / 2 - kernel_half + i] *= blackman);
        }

        /* normalize kernel */
        sum = 1.0f / sum;
        for ( i = 0; i < kernel_half * 2 + 1; i++ )
        {
            int x = kernel_size * 3 / 2 - kernel_half + i;
            kernels [x] *= sum;
            retro_assert( kernels [x] == kernels [x] ); /* catch numerical instability */
        }
    }

    /* generate chroma (iq) filter using gaussian kernel */
    {
        float const cutoff_factor = -0.03125f;
        float cutoff = (float) setup->bleed;
        int i;

        if ( cutoff < 0 )
        {
            /* keep extreme value accessible only near upper end of scale (1.0) */
            cutoff *= cutoff;
            cutoff *= cutoff;
            cutoff *= cutoff;
            cutoff *= -30.0f / 0.65f;
        }
        cutoff = cutoff_factor - 0.65f * cutoff_factor * cutoff;

        for ( i = -kernel_half; i <= kernel_half; i++ )
            kernels [kernel_size / 2 + i] = (float) exp( i * i * cutoff );

        /* normalize even and odd phases separately */
        for ( i = 0; i < 2; i++ )
        {
            float sum = 0;
            int x;
            for ( x = i; x < kernel_size; x += 2 )
                sum += kernels [x];

            sum = 1.0f / sum;
            for ( x = i; x < kernel_size; x += 2 )
            {
                kernels [x] *= sum;
                retro_assert( kernels [x] == kernels [x] ); /* catch numerical instability */
            }
        }
    }

    /*
    printf( "luma:\n" );
    for ( i = kernel_size; i < kernel_size * 2; i++ )
        printf( "%f\n", kernels [i] );
    printf( "chroma:\n" );
    for ( i = 0; i < kernel_size; i++ )
        printf( "%f\n", kernels [i] );
    */

    /* generate linear rescale kernels */
    #if rescale_out > 1
    {
        float weight = 1.0f;
        float* out = impl->kernel;
        int n = rescale_out;
        do
        {
            float remain = 0;
            int i;
            weight -= 1.0f / rescale_in;
            for ( i = 0; i < kernel_size * 2; i++ )
            {
                float cur = kernels [i];
                float m = cur * weight;
                *out++ = m + remain;
                remain = cur - m;
            }
        }
        while ( --n );
    }
    #endif
}

static float const default_decoder [6] =
    { 0.956f, 0.621f, -0.272f, -0.647f, -1.105f, 1.702f };

static void init( init_t* impl, snes_ntsc_setup_t const* setup )
{
    impl->brightness = (float) setup->brightness * (0.5f * rgb_unit) + rgb_offset;
    impl->contrast   = (float) setup->contrast   * (0.5f * rgb_unit) + rgb_unit;
    #ifdef default_palette_contrast
        if ( !setup->palette )
            impl->contrast *= default_palette_contrast;
    #endif

    impl->artifacts = (float) setup->artifacts;
    if ( impl->artifacts > 0 )
        impl->artifacts *= artifacts_max - artifacts_mid;
    impl->artifacts = impl->artifacts * artifacts_mid + artifacts_mid;

    impl->fringing = (float) setup->fringing;
    if ( impl->fringing > 0 )
        impl->fringing *= fringing_max - fringing_mid;
    impl->fringing = impl->fringing * fringing_mid + fringing_mid;

    init_filters( impl, setup );

    /* generate gamma table */
    if ( gamma_size > 1 )
    {
        float const to_float = 1.0f / (gamma_size - (gamma_size > 1));
        float const gamma = 1.1333f - (float) setup->gamma * 0.5f;
        /* match common PC's 2.2 gamma to TV's 2.65 gamma */
        int i;
        for ( i = 0; i < gamma_size; i++ )
            impl->to_float [i] =
                    (float) pow( i * to_float, gamma ) * impl->contrast + impl->brightness;
    }

    /* setup decoder matricies */
    {
        float hue = (float) setup->hue * PI + PI / 180 * ext_decoder_hue;
        float sat = (float) setup->saturation + 1;
        float const* decoder = setup->decoder_matrix;
        if ( !decoder )
        {
            decoder = default_decoder;
            if ( STD_HUE_CONDITION( setup ) )
                hue += PI / 180 * (std_decoder_hue - ext_decoder_hue);
        }

        {
            float s = (float) sin( hue ) * sat;
            float c = (float) cos( hue ) * sat;
            float* out = impl->to_rgb;
            int n;

            n = burst_count;
            do
            {
                float const* in = decoder;
                int n = 3;
                do
                {
                    float i = *in++;
                    float q = *in++;
                    *out++ = i * c - q * s;
                    *out++ = i * s + q * c;
                }
                while ( --n );
                if ( burst_count <= 1 )
                    break;
                ROTATE_IQ( s, c, 0.866025f, -0.5f ); /* +120 degrees */
            }
            while ( --n );
        }
    }
}

/* kernel generation */

#define RGB_TO_YIQ( r, g, b, y, i ) (\
    (y = (r) * 0.299f + (g) * 0.587f + (b) * 0.114f),\
    (i = (r) * 0.596f - (g) * 0.275f - (b) * 0.321f),\
    ((r) * 0.212f - (g) * 0.523f + (b) * 0.311f)\
)

#define YIQ_TO_RGB( y, i, q, to_rgb, type, r, g ) (\
    r = (type) (y + to_rgb [0] * i + to_rgb [1] * q),\
    g = (type) (y + to_rgb [2] * i + to_rgb [3] * q),\
    (type) (y + to_rgb [4] * i + to_rgb [5] * q)\
)

#define PACK_RGB( r, g, b ) ((r) << 21 | (g) << 11 | (b) << 1)

enum { rgb_kernel_size = burst_size / alignment_count };
enum { rgb_bias = rgb_unit * 2 * snes_ntsc_rgb_builder };

typedef struct pixel_info_t
{
    int offset;
    float negate;
    float kernel [4];
} pixel_info_t;

#if rescale_in > 1
    #define PIXEL_OFFSET_( ntsc, scaled ) \
        (kernel_size / 2 + ntsc + (scaled != 0) + (rescale_out - scaled) % rescale_out + \
                (kernel_size * 2 * scaled))

    #define PIXEL_OFFSET( ntsc, scaled ) \
        PIXEL_OFFSET_( ((ntsc) - (scaled) / rescale_out * rescale_in),\
                (((scaled) + rescale_out * 10) % rescale_out) ),\
        (1.0f - (((ntsc) + 100) & 2))
#else
    #define PIXEL_OFFSET( ntsc, scaled ) \
        (kernel_size / 2 + (ntsc) - (scaled)),\
        (1.0f - (((ntsc) + 100) & 2))
#endif

extern pixel_info_t const snes_ntsc_pixels [alignment_count];

/* Generate pixel at all burst phases and column alignments */
static void gen_kernel( init_t* impl, float y, float i, float q, snes_ntsc_rgb_t* out )
{
    /* generate for each scanline burst phase */
    float const* to_rgb = impl->to_rgb;
    int burst_remain = burst_count;
    y -= rgb_offset;
    do
    {
        /* Encode yiq into *two* composite signals (to allow control over artifacting).
        Convolve these with kernels which: filter respective components, apply
        sharpening, and rescale horizontally. Convert resulting yiq to rgb and pack
        into integer. Based on algorithm by NewRisingSun. */
        pixel_info_t const* pixel = snes_ntsc_pixels;
        int alignment_remain = alignment_count;
        do
        {
            /* negate is -1 when composite starts at odd multiple of 2 */
            float const yy = y * impl->fringing * pixel->negate;
            float const ic0 = (i + yy) * pixel->kernel [0];
            float const qc1 = (q + yy) * pixel->kernel [1];
            float const ic2 = (i - yy) * pixel->kernel [2];
            float const qc3 = (q - yy) * pixel->kernel [3];

            float const factor = impl->artifacts * pixel->negate;
            float const ii = i * factor;
            float const yc0 = (y + ii) * pixel->kernel [0];
            float const yc2 = (y - ii) * pixel->kernel [2];

            float const qq = q * factor;
            float const yc1 = (y + qq) * pixel->kernel [1];
            float const yc3 = (y - qq) * pixel->kernel [3];

            float const* k = &impl->kernel [pixel->offset];
            int n;
            ++pixel;
            for ( n = rgb_kernel_size; n; --n )
            {
                float i = k[0]*ic0 + k[2]*ic2;
                float q = k[1]*qc1 + k[3]*qc3;
                float y = k[kernel_size+0]*yc0 + k[kernel_size+1]*yc1 +
                          k[kernel_size+2]*yc2 + k[kernel_size+3]*yc3 + rgb_offset;
                if ( rescale_out <= 1 )
                    k--;
                else if ( k < &impl->kernel [kernel_size * 2 * (rescale_out - 1)] )
                    k += kernel_size * 2 - 1;
                else
                    k -= kernel_size * 2 * (rescale_out - 1) + 2;
                {
                    int r, g, b = YIQ_TO_RGB( y, i, q, to_rgb, int, r, g );
                    *out++ = PACK_RGB( r, g, b ) - rgb_bias;
                }
            }
        }
        while ( alignment_count > 1 && --alignment_remain );

        if ( burst_count <= 1 )
            break;

        to_rgb += 6;

        ROTATE_IQ( i, q, -0.866025f, -0.5f ); /* -120 degrees */
    }
    while ( --burst_remain );
}

static void correct_errors( snes_ntsc_rgb_t color, snes_ntsc_rgb_t* out );

#if DISABLE_CORRECTION
    #define CORRECT_ERROR( a ) { out [i] += rgb_bias; }
    #define DISTRIBUTE_ERROR( a, b, c ) { out [i] += rgb_bias; }
#else
    #define CORRECT_ERROR( a ) { out [a] += error; }
    #define DISTRIBUTE_ERROR( a, b, c ) {\
        snes_ntsc_rgb_t fourth = (error + 2 * snes_ntsc_rgb_builder) >> 2;\
        fourth &= (rgb_bias >> 1) - snes_ntsc_rgb_builder;\
        fourth -= rgb_bias >> 2;\
        out [a] += fourth;\
        out [b] += fourth;\
        out [c] += fourth;\
        out [i] += error - (fourth * 3);\
    }
#endif

#define RGB_PALETTE_OUT( rgb, out_ )\
{\
    unsigned char* out = (out_);\
    snes_ntsc_rgb_t clamped = (rgb);\
    SNES_NTSC_CLAMP_( clamped, (8 - rgb_bits) );\
    out [0] = (unsigned char) (clamped >> 21);\
    out [1] = (unsigned char) (clamped >> 11);\
    out [2] = (unsigned char) (clamped >>  1);\
}

/* blitter related */

#ifndef restrict
    #if defined (__GNUC__)
        #define restrict __restrict__
    #elif defined (_MSC_VER) && _MSC_VER > 1300
        #define restrict __restrict
    #else
        /* no support for restricted pointers */
        #define restrict
    #endif
#endif

#include <limits.h>

#if SNES_NTSC_OUT_DEPTH <= 16
    #if USHRT_MAX == 0xFFFF
        typedef unsigned short snes_ntsc_out_t;
    #else
        #error "Need 16-bit int type"
    #endif

#else
    #if UINT_MAX == 0xFFFFFFFF
        typedef unsigned int  snes_ntsc_out_t;
    #elif ULONG_MAX == 0xFFFFFFFF
        typedef unsigned long snes_ntsc_out_t;
    #else
        #error "Need 32-bit int type"
    #endif

#endif

#endif