Fix GSM decoding: regular GSM and MSGSM do not use the same

bitstream endianness, so they cannot reuse the same code
without a lot of function call overhead.
Thus use templating to compile two different binaries.

Originally committed as revision 25312 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 150 insertions, 0 deletions

diff --git a/libavcodec/gsmdec_template.c b/libavcodec/gsmdec_template.c
new file mode 100644
index 0000000000..b63ec9ed27
--- /dev/null
+++ b/libavcodec/gsmdec_template.c
@@ -0,0 +1,150 @@
+/*
+ * gsm 06.10 decoder
+ * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
+ *
+ * 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
+ * GSM decoder
+ */
+
+#include "get_bits.h"
+#include "gsmdec_data.h"
+
+static void apcm_dequant_add(GetBitContext *gb, int16_t *dst)
+{
+    int i;
+    int maxidx = get_bits(gb, 6);
+    const int16_t *tab = ff_gsm_dequant_tab[maxidx];
+    for (i = 0; i < 13; i++)
+        dst[3*i] += tab[get_bits(gb, 3)];
+}
+
+static inline int gsm_mult(int a, int b)
+{
+    return (a * b + (1 << 14)) >> 15;
+}
+
+static void long_term_synth(int16_t *dst, int lag, int gain_idx)
+{
+    int i;
+    const int16_t *src = dst - lag;
+    uint16_t gain = ff_gsm_long_term_gain_tab[gain_idx];
+    for (i = 0; i < 40; i++)
+        dst[i] = gsm_mult(gain, src[i]);
+}
+
+static inline int decode_log_area(int coded, int factor, int offset)
+{
+    coded <<= 10;
+    coded -= offset;
+    return gsm_mult(coded, factor) << 1;
+}
+
+static av_noinline int get_rrp(int filtered)
+{
+    int abs = FFABS(filtered);
+    if      (abs < 11059) abs <<= 1;
+    else if (abs < 20070) abs += 11059;
+    else                  abs = (abs >> 2) + 26112;
+    return filtered < 0 ? -abs : abs;
+}
+
+static int filter_value(int in, int rrp[8], int v[9])
+{
+    int i;
+    for (i = 7; i >= 0; i--) {
+        in -= gsm_mult(rrp[i], v[i]);
+        v[i + 1] = v[i] + gsm_mult(rrp[i], in);
+    }
+    v[0] = in;
+    return in;
+}
+
+static void short_term_synth(GSMContext *ctx, int16_t *dst, const int16_t *src)
+{
+    int i;
+    int rrp[8];
+    int *lar = ctx->lar[ctx->lar_idx];
+    int *lar_prev = ctx->lar[ctx->lar_idx ^ 1];
+    for (i = 0; i < 8; i++)
+        rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar_prev[i] >> 1) + (lar[i] >> 2));
+    for (i = 0; i < 13; i++)
+        dst[i] = filter_value(src[i], rrp, ctx->v);
+
+    for (i = 0; i < 8; i++)
+        rrp[i] = get_rrp((lar_prev[i] >> 1) + (lar     [i] >> 1));
+    for (i = 13; i < 27; i++)
+        dst[i] = filter_value(src[i], rrp, ctx->v);
+
+    for (i = 0; i < 8; i++)
+        rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar     [i] >> 1) + (lar[i] >> 2));
+    for (i = 27; i < 40; i++)
+        dst[i] = filter_value(src[i], rrp, ctx->v);
+
+    for (i = 0; i < 8; i++)
+        rrp[i] = get_rrp(lar[i]);
+    for (i = 40; i < 160; i++)
+        dst[i] = filter_value(src[i], rrp, ctx->v);
+
+    ctx->lar_idx ^= 1;
+}
+
+static int postprocess(int16_t *data, int msr)
+{
+    int i;
+    for (i = 0; i < 160; i++) {
+        msr = av_clip_int16(data[i] + gsm_mult(msr, 28180));
+        data[i] = av_clip_int16(msr << 1) & ~7;
+    }
+    return msr;
+}
+
+static int gsm_decode_block(AVCodecContext *avctx, int16_t *samples,
+                            GetBitContext *gb)
+{
+    GSMContext *ctx = avctx->priv_data;
+    int i;
+    int16_t *ref_dst = ctx->ref_buf + 120;
+    int *lar = ctx->lar[ctx->lar_idx];
+    lar[0] = decode_log_area(get_bits(gb, 6), 13107,  1 << 15);
+    lar[1] = decode_log_area(get_bits(gb, 6), 13107,  1 << 15);
+    lar[2] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) + 2048*2);
+    lar[3] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) - 2560*2);
+    lar[4] = decode_log_area(get_bits(gb, 4), 19223, (1 << 13) +   94*2);
+    lar[5] = decode_log_area(get_bits(gb, 4), 17476, (1 << 13) - 1792*2);
+    lar[6] = decode_log_area(get_bits(gb, 3), 31454, (1 << 12) -  341*2);
+    lar[7] = decode_log_area(get_bits(gb, 3), 29708, (1 << 12) - 1144*2);
+
+    for (i = 0; i < 4; i++) {
+        int lag      = get_bits(gb, 7);
+        int gain_idx = get_bits(gb, 2);
+        int offset   = get_bits(gb, 2);
+        lag = av_clip(lag, 40, 120);
+        long_term_synth(ref_dst, lag, gain_idx);
+        apcm_dequant_add(gb, ref_dst + offset);
+        ref_dst += 40;
+    }
+    memcpy(ctx->ref_buf, ctx->ref_buf + 160, 120 * sizeof(*ctx->ref_buf));
+    short_term_synth(ctx, samples, ctx->ref_buf + 120);
+    // for optimal speed this could be merged with short_term_synth,
+    // not done yet because it is a bit ugly
+    ctx->msr = postprocess(samples, ctx->msr);
+    return 0;
+}