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avcodec/cbs: add helper functions and macros to read and write signed values

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Reviewed-by: Mark Thompson <sw@jkqxz.net>
Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
James Almer 2019-04-15 17:46:53 -03:00
parent cfe220332a
commit 5006dcdf9a
2 changed files with 98 additions and 1 deletions
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79
libavcodec/cbs.c
View File

@ -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,

20
libavcodec/cbs_internal.h
View File

@ -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;