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Separate crc32 and crc32_combine tables so the crc32_combine tables a…
…re not included when not used if statically linking. Reduces code size by 4k.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,108 @@ | ||
| /* crc32_comb.c -- compute the CRC-32 of a data stream | ||
| * Copyright (C) 1995-2006, 2010, 2011, 2012, 2016, 2018 Mark Adler | ||
| * For conditions of distribution and use, see copyright notice in zlib.h | ||
| * | ||
| * Thanks to Rodney Brown <[email protected]> for his contribution of faster | ||
| * CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing | ||
| * tables for updating the shift register in one step with three exclusive-ors | ||
| * instead of four steps with four exclusive-ors. This results in about a | ||
| * factor of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3. | ||
| */ | ||
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| #include "zbuild.h" | ||
| #include <inttypes.h> | ||
| #include "deflate.h" | ||
| #include "crc32_p.h" | ||
| #include "crc32_comb_tbl.h" | ||
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| /* Local functions for crc concatenation */ | ||
| static uint32_t crc32_combine_(uint32_t crc1, uint32_t crc2, z_off64_t len2); | ||
| static void crc32_combine_gen_(uint32_t *op, z_off64_t len2); | ||
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| /* ========================================================================= */ | ||
| static uint32_t crc32_combine_(uint32_t crc1, uint32_t crc2, z_off64_t len2) { | ||
| int n; | ||
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| if (len2 > 0) | ||
| /* operator for 2^n zeros repeats every GF2_DIM n values */ | ||
| for (n = 0; len2; n = (n + 1) % GF2_DIM, len2 >>= 1) | ||
| if (len2 & 1) | ||
| crc1 = gf2_matrix_times(crc_comb[n], crc1); | ||
| return crc1 ^ crc2; | ||
| } | ||
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| /* ========================================================================= */ | ||
| #ifdef ZLIB_COMPAT | ||
| unsigned long Z_EXPORT PREFIX(crc32_combine)(unsigned long crc1, unsigned long crc2, z_off_t len2) { | ||
| return (unsigned long)crc32_combine_((uint32_t)crc1, (uint32_t)crc2, len2); | ||
| } | ||
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| unsigned long Z_EXPORT PREFIX4(crc32_combine)(unsigned long crc1, unsigned long crc2, z_off64_t len2) { | ||
| return (unsigned long)crc32_combine_((uint32_t)crc1, (uint32_t)crc2, len2); | ||
| } | ||
| #else | ||
| uint32_t Z_EXPORT PREFIX4(crc32_combine)(uint32_t crc1, uint32_t crc2, z_off64_t len2) { | ||
| return crc32_combine_(crc1, crc2, len2); | ||
| } | ||
| #endif | ||
|
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| /* ========================================================================= */ | ||
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| static void crc32_combine_gen_(uint32_t *op, z_off64_t len2) { | ||
| uint32_t row; | ||
| int j; | ||
| unsigned i; | ||
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| /* if len2 is zero or negative, return the identity matrix */ | ||
| if (len2 <= 0) { | ||
| row = 1; | ||
| for (j = 0; j < GF2_DIM; j++) { | ||
| op[j] = row; | ||
| row <<= 1; | ||
| } | ||
| return; | ||
| } | ||
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| /* at least one bit in len2 is set -- find it, and copy the operator | ||
| corresponding to that position into op */ | ||
| i = 0; | ||
| for (;;) { | ||
| if (len2 & 1) { | ||
| for (j = 0; j < GF2_DIM; j++) | ||
| op[j] = crc_comb[i][j]; | ||
| break; | ||
| } | ||
| len2 >>= 1; | ||
| i = (i + 1) % GF2_DIM; | ||
| } | ||
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| /* for each remaining bit set in len2 (if any), multiply op by the operator | ||
| corresponding to that position */ | ||
| for (;;) { | ||
| len2 >>= 1; | ||
| i = (i + 1) % GF2_DIM; | ||
| if (len2 == 0) | ||
| break; | ||
| if (len2 & 1) | ||
| for (j = 0; j < GF2_DIM; j++) | ||
| op[j] = gf2_matrix_times(crc_comb[i], op[j]); | ||
| } | ||
| } | ||
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| /* ========================================================================= */ | ||
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| #ifdef ZLIB_COMPAT | ||
| void Z_EXPORT PREFIX(crc32_combine_gen)(uint32_t *op, z_off_t len2) { | ||
| crc32_combine_gen_(op, len2); | ||
| } | ||
| #endif | ||
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| void Z_EXPORT PREFIX4(crc32_combine_gen)(uint32_t *op, z_off64_t len2) { | ||
| crc32_combine_gen_(op, len2); | ||
| } | ||
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| /* ========================================================================= */ | ||
| uint32_t Z_EXPORT PREFIX(crc32_combine_op)(uint32_t crc1, uint32_t crc2, const uint32_t *op) { | ||
| return gf2_matrix_times(op, crc1) ^ crc2; | ||
| } |
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