b7dfbbcda
Denys Vlasenko
2018-01-31
Subject
gzip: speed up send_bits()
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Commit Diff GitHub →
archival/gzip.c+6 -6
| @@ -523,7 +523,6 @@ static unsigned file_read(void *buf, unsigned size) | |
| static void send_bits(unsigned value, unsigned length) | |
| { | |
| unsigned new_buf; | |
| - | unsigned remain; |
| #ifdef DEBUG | |
| Tracev((stderr, " l %2d v %4x ", length, value)); | |
| @@ -534,25 +533,26 @@ static void send_bits(unsigned value, unsigned length) | |
| new_buf = G1.bi_buf | (value << G1.bi_valid); | |
| /* NB: the above may sometimes do "<< 32" shift (undefined) | |
| - | * if check below is changed to "length > remain" instead of >= */ |
| - | remain = BUF_SIZE - G1.bi_valid; |
| + | * if check below is changed to "length > BUF_SIZE" instead of >= */ |
| + | length += G1.bi_valid; |
| /* If bi_buf is full */ | |
| - | if (length >= remain) { |
| + | if (length >= BUF_SIZE) { |
| /* ...use (valid) bits from bi_buf and | |
| * (BUF_SIZE - bi_valid) bits from value, | |
| * leaving (width - (BUF_SIZE-bi_valid)) unused bits in value. | |
| */ | |
| + | value >>= (BUF_SIZE - G1.bi_valid); |
| if (BUF_SIZE == 32) { | |
| put_32bit(new_buf); /* maybe unroll to 2*put_16bit()? */ | |
| } else { /* 16 */ | |
| put_16bit(new_buf); | |
| } | |
| - | new_buf = value >> remain; |
| + | new_buf = value; |
| length -= BUF_SIZE; | |
| } | |
| G1.bi_buf = new_buf; | |
| - | G1.bi_valid += length; |
| + | G1.bi_valid = length; |
| } | |