From 5006dcdf9af177444e3e0185640d7d84629e4215 Mon Sep 17 00:00:00 2001 From: James Almer Date: Mon, 15 Apr 2019 17:46:53 -0300 Subject: avcodec/cbs: add helper functions and macros to read and write signed values Reviewed-by: Mark Thompson Signed-off-by: James Almer --- libavcodec/cbs.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++ libavcodec/cbs_internal.h | 20 +++++++++++- 2 files changed, 98 insertions(+), 1 deletion(-) (limited to 'libavcodec') diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c index c388be896b..0260ba6f67 100644 --- a/libavcodec/cbs.c +++ b/libavcodec/cbs.c @@ -504,6 +504,85 @@ int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc, return 0; } +int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc, + int width, const char *name, + const int *subscripts, int32_t *write_to, + int32_t range_min, int32_t range_max) +{ + int32_t value; + int position; + + av_assert0(width > 0 && width <= 32); + + if (get_bits_left(gbc) < width) { + av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid value at " + "%s: bitstream ended.\n", name); + return AVERROR_INVALIDDATA; + } + + if (ctx->trace_enable) + position = get_bits_count(gbc); + + value = get_sbits_long(gbc, width); + + if (ctx->trace_enable) { + char bits[33]; + int i; + for (i = 0; i < width; i++) + bits[i] = value & (1U << (width - i - 1)) ? '1' : '0'; + bits[i] = 0; + + ff_cbs_trace_syntax_element(ctx, position, name, subscripts, + bits, value); + } + + if (value < range_min || value > range_max) { + av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: " + "%"PRId32", but must be in [%"PRId32",%"PRId32"].\n", + name, value, range_min, range_max); + return AVERROR_INVALIDDATA; + } + + *write_to = value; + return 0; +} + +int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc, + int width, const char *name, + const int *subscripts, int32_t value, + int32_t range_min, int32_t range_max) +{ + av_assert0(width > 0 && width <= 32); + + if (value < range_min || value > range_max) { + av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: " + "%"PRId32", but must be in [%"PRId32",%"PRId32"].\n", + name, value, range_min, range_max); + return AVERROR_INVALIDDATA; + } + + if (put_bits_left(pbc) < width) + return AVERROR(ENOSPC); + + if (ctx->trace_enable) { + char bits[33]; + int i; + for (i = 0; i < width; i++) + bits[i] = value & (1U << (width - i - 1)) ? '1' : '0'; + bits[i] = 0; + + ff_cbs_trace_syntax_element(ctx, put_bits_count(pbc), + name, subscripts, bits, value); + } + + if (width < 32) + put_sbits(pbc, width, value); + else + put_bits32(pbc, value); + + return 0; +} + int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, diff --git a/libavcodec/cbs_internal.h b/libavcodec/cbs_internal.h index 53f2e5d187..dd4babf092 100644 --- a/libavcodec/cbs_internal.h +++ b/libavcodec/cbs_internal.h @@ -81,10 +81,28 @@ int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc, const int *subscripts, uint32_t value, uint32_t range_min, uint32_t range_max); -// The largest value representable in N bits, suitable for use as +int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc, + int width, const char *name, + const int *subscripts, int32_t *write_to, + int32_t range_min, int32_t range_max); + +int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc, + int width, const char *name, + const int *subscripts, int32_t value, + int32_t range_min, int32_t range_max); + +// The largest unsigned value representable in N bits, suitable for use as // range_max in the above functions. #define MAX_UINT_BITS(length) ((UINT64_C(1) << (length)) - 1) +// The largest signed value representable in N bits, suitable for use as +// range_max in the above functions. +#define MAX_INT_BITS(length) ((INT64_C(1) << ((length) - 1)) - 1) + +// The smallest signed value representable in N bits, suitable for use as +// range_min in the above functions. +#define MIN_INT_BITS(length) (-(INT64_C(1) << ((length) - 1))) + extern const CodedBitstreamType ff_cbs_type_av1; extern const CodedBitstreamType ff_cbs_type_h264; -- cgit v1.2.3