Rename ffmpeg-4.2-fit to ffmpeg-4-fit

trunk/3rdparty/ffmpeg-4-fit/libavcodec/dirac_arith.h

@@ -0,0 +1,202 @@
+/*
+ * Copyright (C) 2007 Marco Gerards <marco@gnu.org>
+ * Copyright (C) 2009 David Conrad
+ *
+ * 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
+ * Arithmetic decoder for Dirac
+ * @author Marco Gerards <marco@gnu.org>
+ */
+
+#ifndef AVCODEC_DIRAC_ARITH_H
+#define AVCODEC_DIRAC_ARITH_H
+
+#include "libavutil/x86/asm.h"
+#include "bytestream.h"
+#include "get_bits.h"
+
+enum dirac_arith_contexts {
+    CTX_ZPZN_F1,
+    CTX_ZPNN_F1,
+    CTX_NPZN_F1,
+    CTX_NPNN_F1,
+    CTX_ZP_F2,
+    CTX_ZP_F3,
+    CTX_ZP_F4,
+    CTX_ZP_F5,
+    CTX_ZP_F6,
+    CTX_NP_F2,
+    CTX_NP_F3,
+    CTX_NP_F4,
+    CTX_NP_F5,
+    CTX_NP_F6,
+    CTX_COEFF_DATA,
+    CTX_SIGN_NEG,
+    CTX_SIGN_ZERO,
+    CTX_SIGN_POS,
+    CTX_ZERO_BLOCK,
+    CTX_DELTA_Q_F,
+    CTX_DELTA_Q_DATA,
+    CTX_DELTA_Q_SIGN,
+
+    DIRAC_CTX_COUNT
+};
+
+// Dirac resets the arith decoder between decoding various types of data,
+// so many contexts are never used simultaneously. Thus, we can reduce
+// the number of contexts needed by reusing them.
+#define CTX_SB_F1        CTX_ZP_F5
+#define CTX_SB_DATA      0
+#define CTX_PMODE_REF1   0
+#define CTX_PMODE_REF2   1
+#define CTX_GLOBAL_BLOCK 2
+#define CTX_MV_F1        CTX_ZP_F2
+#define CTX_MV_DATA      0
+#define CTX_DC_F1        CTX_ZP_F5
+#define CTX_DC_DATA      0
+
+typedef struct {
+    unsigned low;
+    uint16_t range;
+    int16_t  counter;
+
+    const uint8_t *bytestream;
+    const uint8_t *bytestream_end;
+
+    uint16_t contexts[DIRAC_CTX_COUNT];
+    int error;
+    int overread;
+} DiracArith;
+
+extern const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT];
+extern const uint16_t ff_dirac_prob[256];
+extern int16_t ff_dirac_prob_branchless[256][2];
+
+static inline void renorm(DiracArith *c)
+{
+#if HAVE_FAST_CLZ
+    int shift = 14 - av_log2_16bit(c->range-1) + ((c->range-1)>>15);
+
+    c->low    <<= shift;
+    c->range  <<= shift;
+    c->counter += shift;
+#else
+    while (c->range <= 0x4000) {
+        c->low   <<= 1;
+        c->range <<= 1;
+        c->counter++;
+    }
+#endif
+}
+
+static inline void refill(DiracArith *c)
+{
+    int counter = c->counter;
+
+    if (counter >= 0) {
+        int new = bytestream_get_be16(&c->bytestream);
+
+        // the spec defines overread bits to be 1, and streams rely on this
+        if (c->bytestream > c->bytestream_end) {
+            new |= 0xff;
+            if (c->bytestream > c->bytestream_end+1)
+                new |= 0xff00;
+
+            c->bytestream = c->bytestream_end;
+            c->overread ++;
+            if (c->overread > 4)
+                c->error = AVERROR_INVALIDDATA;
+        }
+
+        c->low += new << counter;
+        counter -= 16;
+    }
+    c->counter = counter;
+}
+
+static inline int dirac_get_arith_bit(DiracArith *c, int ctx)
+{
+    int prob_zero = c->contexts[ctx];
+    int range_times_prob, bit;
+    unsigned low = c->low;
+    int    range = c->range;
+
+    range_times_prob = (c->range * prob_zero) >> 16;
+
+#if ARCH_X86 && HAVE_FAST_CMOV && HAVE_INLINE_ASM && HAVE_6REGS
+    low   -= range_times_prob << 16;
+    range -= range_times_prob;
+    bit = 0;
+    __asm__(
+        "cmpl   %5, %4 \n\t"
+        "setae  %b0    \n\t"
+        "cmovb  %3, %2 \n\t"
+        "cmovb  %5, %1 \n\t"
+        : "+q"(bit), "+r"(range), "+r"(low)
+        : "r"(c->low), "r"(c->low>>16),
+          "r"(range_times_prob)
+    );
+#else
+    bit = (low >> 16) >= range_times_prob;
+    if (bit) {
+        low   -= range_times_prob << 16;
+        range -= range_times_prob;
+    } else {
+        range  = range_times_prob;
+    }
+#endif
+
+    c->contexts[ctx] += ff_dirac_prob_branchless[prob_zero>>8][bit];
+    c->low   = low;
+    c->range = range;
+
+    renorm(c);
+    refill(c);
+    return bit;
+}
+
+static inline int dirac_get_arith_uint(DiracArith *c, int follow_ctx, int data_ctx)
+{
+    int ret = 1;
+    while (!dirac_get_arith_bit(c, follow_ctx)) {
+        if (ret >= 0x40000000) {
+            av_log(NULL, AV_LOG_ERROR, "dirac_get_arith_uint overflow\n");
+            c->error = AVERROR_INVALIDDATA;
+            return -1;
+        }
+        ret <<= 1;
+        ret += dirac_get_arith_bit(c, data_ctx);
+        follow_ctx = ff_dirac_next_ctx[follow_ctx];
+    }
+    return ret-1;
+}
+
+static inline int dirac_get_arith_int(DiracArith *c, int follow_ctx, int data_ctx)
+{
+    int ret = dirac_get_arith_uint(c, follow_ctx, data_ctx);
+    if (ret && dirac_get_arith_bit(c, data_ctx+1))
+        ret = -ret;
+    return ret;
+}
+
+void ff_dirac_init_arith_tables(void);
+void ff_dirac_init_arith_decoder(DiracArith *c, GetBitContext *gb, int length);
+
+#endif /* AVCODEC_DIRAC_ARITH_H */