[FFmpeg-devel] [PATCH 1/3] avcodec/webp: Use uint8_t for code lengths

["zhilizhao(赵志立)"]

> On Oct 26, 2020, at 3:24 PM, Andreas Rheinhardt <andreas.rheinhardt at gmail.com> wrote:
> 
> Andreas Rheinhardt:
>> They are always in the range 0..15, so using an int is not necessary.
>> Furthermore, using an int would not work if sizeof(int) == 4 as

You mean if sizeof(int) != 4 ?

>> ff_init_vlc_sparse() can only handle uint8_t, uint16_t and uint32_t
>> lengths.
>> 
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>> libavcodec/webp.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/libavcodec/webp.c b/libavcodec/webp.c
>> index 6140c7ea4a..6b53a7f17c 100644
>> --- a/libavcodec/webp.c
>> +++ b/libavcodec/webp.c
>> @@ -243,7 +243,7 @@ static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb)
>>         return get_vlc2(gb, r->vlc.table, 8, 2);
>> }
>> 
>> -static int huff_reader_build_canonical(HuffReader *r, int *code_lengths,
>> +static int huff_reader_build_canonical(HuffReader *r, const uint8_t *code_lengths,
>>                                        int alphabet_size)
>> {
>>     int len = 0, sym, code = 0, ret;
>> @@ -324,8 +324,8 @@ static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,
>>                                     int alphabet_size)
>> {
>>     HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };
>> -    int *code_lengths = NULL;
>> -    int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
>> +    uint8_t *code_lengths = NULL;
>> +    uint8_t code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
>>     int i, symbol, max_symbol, prev_code_len, ret;
>>     int num_codes = 4 + get_bits(&s->gb, 4);
>> 
>> @@ -340,7 +340,7 @@ static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,
>>     if (ret < 0)
>>         goto finish;
>> 
>> -    code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));
>> +    code_lengths = av_mallocz(alphabet_size);
>>     if (!code_lengths) {
>>         ret = AVERROR(ENOMEM);
>>         goto finish;
>> 
> Will apply this patchset later today unless there are objections.
> 
> - Andreas
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