Patch by Mohamed Tarek from FS#10182 - convert codec to fixed-point using patches submitted to the ffmpeg mailing list in 2007 by Ian Braithwaite.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20901 a1c6a512-1295-4272-9138-f99709370657

apps/codecs/libcook/cook_fixpoint.h

@@ -0,0 +1,243 @@
+/*
+ * COOK compatible decoder, fixed point implementation.
+ * Copyright (c) 2007 Ian Braithwaite
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+/**
+ * @file cook_float.h
+ *
+ * Cook AKA RealAudio G2 fixed point functions.
+ *
+ * Fixed point values are represented as 32 bit signed integers,
+ * which can be added and subtracted directly in C (without checks for
+ * overflow/saturation.
+ * Two multiplication routines are provided:
+ * 1) Multiplication by powers of two (2^-31 .. 2^31), implemented
+ *    with C's bit shift operations.
+ * 2) Multiplication by 16 bit fractions (0 <= x < 1), implemented
+ *    in C using two 32 bit integer multiplications.
+ */
+
+/**
+ * Initialise fixed point implementation.
+ * Nothing to do for fixed point.
+ *
+ * @param q                     pointer to the COOKContext
+ */
+static inline int init_cook_math(COOKContext *q)
+{
+    return 0;
+}
+
+/**
+ * Free resources used by floating point implementation.
+ * Nothing to do for fixed point.
+ *
+ * @param q                     pointer to the COOKContext
+ */
+static inline void free_cook_math(COOKContext *q)
+{
+    return;
+}
+
+
+/**
+ * Fixed point multiply by power of two.
+ *
+ * @param x                     fix point value
+ * @param i                     integer power-of-two, -31..+31
+ */
+static inline FIXP fixp_pow2(FIXP x, int i)
+{
+  if (i < 0)
+    return (x >> -i) + ((x >> (-i-1)) & 1);
+  else
+    return x << i;              /* no check for overflow */
+}
+
+/**
+ * Fixed point multiply by fraction.
+ *
+ * @param a                     fix point value
+ * @param b                     fix point fraction, 0 <= b < 1
+ */
+static inline FIXP fixp_mult_su(FIXP a, FIXPU b)
+{
+    int32_t hb = (a >> 16) * b;
+    uint32_t lb = (a & 0xffff) * b;
+
+    return hb + (lb >> 16) + ((lb & 0x8000) >> 15);
+}
+
+
+/**
+ * The real requantization of the mltcoefs
+ *
+ * @param q                     pointer to the COOKContext
+ * @param index                 index
+ * @param quant_index           quantisation index for this band
+ * @param subband_coef_index    array of indexes to quant_centroid_tab
+ * @param subband_coef_sign     use random noise instead of predetermined value
+ * @param mlt_ptr               pointer to the mlt coefficients
+ */
+static void scalar_dequant_math(COOKContext *q, int index,
+                                int quant_index, int* subband_coef_index,
+                                int* subband_coef_sign, REAL_T *mlt_p)
+{
+    /* Num. half bits to right shift */
+    const int s = 33 - quant_index + av_log2(q->samples_per_channel);
+    const FIXP *table = quant_tables[s & 1][index];
+    FIXP f;
+    int i;
+
+    for(i=0 ; i<SUBBAND_SIZE ; i++) {
+        f = table[subband_coef_index[i]];
+        /* noise coding if subband_coef_index[i] == 0 */
+        if (((subband_coef_index[i] == 0) && av_lfg_get(&q->random_state) < 0x80000000) ||
+            ((subband_coef_index[i] != 0) && subband_coef_sign[i]))
+            f = -f;
+
+        mlt_p[i] = (s >= 64) ? 0 : fixp_pow2(f, -(s/2));
+    }
+}
+
+
+/**
+ * The modulated lapped transform, this takes transform coefficients
+ * and transforms them into timedomain samples.
+ * A window step is also included.
+ *
+ * @param q                 pointer to the COOKContext
+ * @param inbuffer          pointer to the mltcoefficients
+ * @param outbuffer         pointer to the timedomain buffer
+ * @param mlt_tmp           pointer to temporary storage space
+ */
+#include "cook_fixp_mdct.h"
+
+static inline void imlt_math(COOKContext *q, FIXP *in)
+{
+    const int n = q->samples_per_channel;
+    const int step = 4 << (10 - av_log2(n));
+    int i = 0, j = step>>1;
+
+    cook_mdct_backward(2 * n, in, q->mono_mdct_output);
+
+    do {
+        FIXP tmp = q->mono_mdct_output[i];
+        
+        q->mono_mdct_output[i] =
+          fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j]);
+        q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j+1]);
+        j += step;
+    } while (++i < n/2);
+    do {
+        FIXP tmp = q->mono_mdct_output[i];
+        
+        j -= step;
+        q->mono_mdct_output[i] =
+          fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j+1]);
+        q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j]);
+    } while (++i < n);
+}
+
+
+/**
+ * Perform buffer overlapping.
+ *
+ * @param q                 pointer to the COOKContext
+ * @param gain              gain correction to apply first to output buffer
+ * @param buffer            data to overlap
+ */
+static inline void overlap_math(COOKContext *q, int gain, FIXP buffer[])
+{
+    int i;
+    for(i=0 ; i<q->samples_per_channel ; i++) {
+        q->mono_mdct_output[i] =
+          fixp_pow2(q->mono_mdct_output[i], gain) + buffer[i];
+    }
+}
+
+
+/**
+ * the actual requantization of the timedomain samples
+ *
+ * @param q                 pointer to the COOKContext
+ * @param buffer            pointer to the timedomain buffer
+ * @param gain_index        index for the block multiplier
+ * @param gain_index_next   index for the next block multiplier
+ */
+static inline void
+interpolate_math(COOKContext *q, FIXP* buffer,
+                 int gain_index, int gain_index_next)
+{
+    int i;
+    int gain_size_factor = q->samples_per_channel / 8;
+
+    if(gain_index == gain_index_next){              //static gain
+        for(i = 0; i < gain_size_factor; i++) {
+            buffer[i] = fixp_pow2(buffer[i], gain_index);
+        }
+    } else {                                        //smooth gain
+        int step = (gain_index_next - gain_index)
+                   << (7 - av_log2(gain_size_factor));
+        int x = 0;
+
+        for(i = 0; i < gain_size_factor; i++) {
+            buffer[i] = fixp_mult_su(buffer[i], pow128_tab[x]);
+            buffer[i] = fixp_pow2(buffer[i], gain_index+1);
+
+            x += step;
+            gain_index += (x + 128) / 128 - 1;
+            x = (x + 128) % 128;
+        }
+    }
+}
+
+
+/**
+ * Decoupling calculation for joint stereo coefficients.
+ *
+ * @param x                 mono coefficient
+ * @param table             number of decoupling table
+ * @param i                 table index
+ */
+static inline FIXP cplscale_math(FIXP x, int table, int i)
+{
+  return fixp_mult_su(x, cplscales[table-2][i]);
+}
+
+
+/**
+ * Final converion from floating point values to
+ * signed, 16 bit sound samples. Round and clip.
+ *
+ * @param q                 pointer to the COOKContext
+ * @param out               pointer to the output buffer
+ * @param chan              0: left or single channel, 1: right channel
+ */
+static inline void output_math(COOKContext *q, int16_t *out, int chan)
+{
+    int j;
+
+    for (j = 0; j < q->samples_per_channel; j++) {
+        out[chan + q->nb_channels * j] =
+          av_clip(fixp_pow2(q->mono_mdct_output[j], -11), -32768, 32767);
+    }
+}