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[188.193.170.75]) by smtp.gmail.com with ESMTPSA id l24sm2572543wmi.7.2020.11.10.02.50.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2020 02:50:23 -0800 (PST) From: Andreas Rheinhardt To: ffmpeg-devel@ffmpeg.org Date: Tue, 10 Nov 2020 11:48:02 +0100 Message-Id: <20201110104851.321029-66-andreas.rheinhardt@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201110104851.321029-1-andreas.rheinhardt@gmail.com> References: <20201110104851.321029-1-andreas.rheinhardt@gmail.com> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 065/114] avcodec/mjpegdec: Simplify creating VLC table X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Cc: Andreas Rheinhardt Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" ff_init_vlc_from_lengths() can be used to offload the computation of the codes; it also allows to omit the check whether the codes are already properly ordered (they are). Signed-off-by: Andreas Rheinhardt --- libavcodec/mjpegdec.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index 147dd819e5..2a226f63d4 100644 --- a/libavcodec/mjpegdec.c +++ b/libavcodec/mjpegdec.c @@ -50,18 +50,14 @@ #include "bytestream.h" -static void build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, - const uint8_t *bits_table) +static void build_huffman_codes(uint8_t *huff_size, const uint8_t *bits_table) { - for (int i = 1, code = 0, k = 0; i <= 16; i++) { + for (int i = 1, k = 0; i <= 16; i++) { int nb = bits_table[i]; for (int j = 0; j < nb;j++) { huff_size[k] = i; - huff_code[k] = code; - code++; k++; } - code <<= 1; } } @@ -70,13 +66,12 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table, int is_ac) { uint8_t huff_size[256]; - uint16_t huff_code[256]; uint16_t huff_sym[256]; int i; av_assert0(nb_codes <= 256); - build_huffman_codes(huff_size, huff_code, bits_table); + build_huffman_codes(huff_size, bits_table); for (i = 0; i < nb_codes; i++) { huff_sym[i] = val_table[i] + 16 * is_ac; @@ -85,8 +80,8 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table, huff_sym[i] = 16 * 256; } - return ff_init_vlc_sparse(vlc, 9, nb_codes, huff_size, 1, 1, - huff_code, 2, 2, huff_sym, 2, 2, 0); + return ff_init_vlc_from_lengths(vlc, 9, nb_codes, huff_size, 1, + huff_sym, 2, 2, 0, 0); } static int init_default_huffman_tables(MJpegDecodeContext *s)