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https://github.com/shadps4-emu/ext-cryptopp.git
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Cleanup donna_32.cpp arithmetic shift
This commit is contained in:
Jeffrey Walton
parent
a09d4024b7
commit
459035fcaa
95
donna_32.cpp
95
donna_32.cpp
@ -56,10 +56,9 @@
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#include "stdcpp.h"
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#include "cpu.h"
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// This macro is not in a header like config.h because
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// we don't want it exposed to user code. We also need
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// a standard header like <stdint.h> or <stdef.h>.
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// Langley uses uint128_t in the 64-bit code paths so
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// This macro is not in a header like config.h because we don't want it
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// exposed to user code. We also need a standard header like <stdint.h>
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// or <stdef.h>. Langley uses uint128_t in the 64-bit code paths so
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// we further restrict 64-bit code.
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#if (UINTPTR_MAX == 0xffffffff) || !defined(CRYPTOPP_WORD128_AVAILABLE)
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# define CRYPTOPP_32BIT 1
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@ -67,6 +66,16 @@
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# define CRYPTOPP_64BIT 1
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#endif
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// Some compilers don't handle the code for the arithmetic shifts well.
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// For compilers we know how to support we will issue the asm to sidestep
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// believe the problem. We also switch to a slightly different pattern.
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// We believe the pattern preserves the existing properties without a
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// branch. The ASM uses one intruction, while the C statement use 2 to 6
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// instructions, depending on the compiler.
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#if (__GNUC__ >= 3) || (__SUNPRO_CC >= 0x5100)
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# define CRYPTOPP_ASR_ASM 1
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#endif
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// Squash MS LNK4221 and libtool warnings
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extern const char DONNA32_FNAME[] = __FILE__;
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@ -84,41 +93,53 @@ using CryptoPP::sword64;
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typedef sword64 limb;
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// Added by JW for SunCC. Avoid the bit twiddling hacks.
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template <unsigned int S>
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inline int SignExtend(int val)
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{
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#if (__GNUC__ >= 3) || (__SUNPRO_CC >= 0x5100)
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# if CRYPTOPP_BOOL_X86
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#if defined(CRYPTOPP_ASR_ASM) && (CRYPTOPP_BOOL_X86)
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__asm__
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(
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"sar $31, %0 \n"
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: "+g" (val) : : "cc"
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"sar %1, %0 \n"
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: "+g" (val) : "I" (S) : "cc"
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);
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return val;
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# endif
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// TODO: ARM
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#endif
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#elif defined(CRYPTOPP_ASR_ASM) && (CRYPTOPP_BOOL_ARM32)
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__asm__
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(
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"asr %0, %0, %1 \n"
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: "+r" (val) : "I" (S) :
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);
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return val;
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#else
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// GCC and SunCC compile down to a shift and neg.
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return (val >> 31) * -1;
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// Also see the comments for CRYPTOPP_ASR_ASM.
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return (val >> S) * -1;
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#endif
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}
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// Added by JW for SunCC. Avoid the bit twiddling hacks.
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template <unsigned int S>
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inline unsigned int SignExtend(unsigned int val)
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{
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#if (__GNUC__ >= 3) || (__SUNPRO_CC >= 0x5100)
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# if CRYPTOPP_BOOL_X86
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#if defined(CRYPTOPP_ASR_ASM) && (CRYPTOPP_BOOL_X86)
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__asm__
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(
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"sar $31, %0 \n"
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: "+g" (val) : : "cc"
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"sar %1, %0 \n"
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: "+g" (val) : "I" (S) : "cc"
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);
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return val;
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# endif
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// TODO: ARM
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#endif
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#elif defined(CRYPTOPP_ASR_ASM) && (CRYPTOPP_BOOL_ARM32)
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__asm__
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(
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"asr %0, %0, %1 \n"
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: "+r" (val) : "I" (S) :
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);
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return val;
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#else
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// GCC and SunCC compile down to a shift and neg.
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return (unsigned int)(((signed int)(val >> 31)) * -1);
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// Also see the comments for CRYPTOPP_ASR_ASM.
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const signed int v = (signed int)(val >> S)
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return (unsigned int)(v * -1);
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#endif
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}
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/* Field element representation:
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@ -304,7 +325,7 @@ void freduce_degree(limb *output)
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output[0] += output[10];
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}
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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// #if (-1 & 3) != 3
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// #error "This code only works on a two's complement system"
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// #endif
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@ -317,13 +338,15 @@ inline limb div_by_2_26(const limb v)
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/* High word of v; no shift needed. */
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const word32 highword = (word32) (((word64) v) >> 32);
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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/* Set to all 1s if v was negative; else set to 0s. */
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/* const sword32 sign = ((sword32) highword) >> 31; */
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const sword32 sign = SignExtend(highword);
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const word32 sign = SignExtend<31>(highword);
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/* Set to 0x3ffffff if v was negative; else set to 0. */
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const sword32 roundoff = ((word32) sign) >> 6;
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/* const sword32 roundoff = ((word32) sign) >> 6; */
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const sword32 roundoff = (sword32)(sign >> 6);
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/* Should return v / (1<<26) */
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return (v + roundoff) >> 26;
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}
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@ -336,13 +359,15 @@ inline limb div_by_2_25(const limb v)
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/* High word of v; no shift needed*/
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const word32 highword = (word32) (((word64) v) >> 32);
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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/* Set to all 1s if v was negative; else set to 0s. */
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/* const sword32 sign = ((sword32) highword) >> 31; */
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const sword32 sign = SignExtend(highword);
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const word32 sign = SignExtend<31>(highword);
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/* Set to 0x1ffffff if v was negative; else set to 0. */
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const sword32 roundoff = ((word32) sign) >> 7;
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/* const sword32 roundoff = ((word32) sign) >> 7; */
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const sword32 roundoff = (sword32)(sign >> 7);
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/* Should return v / (1<<25) */
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return (v + roundoff) >> 25;
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}
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@ -517,7 +542,7 @@ void fexpand(limb *output, const byte *input)
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#undef F
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}
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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// #if (-32 >> 1) != -16
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// #error "This code only works when >> does sign-extension on negative numbers"
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// #endif
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@ -525,7 +550,7 @@ void fexpand(limb *output, const byte *input)
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/* sword32_eq returns 0xffffffff iff a == b and zero otherwise. */
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sword32 sword32_eq(sword32 a, sword32 b)
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{
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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a = ~(a ^ b);
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a &= a << 16;
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a &= a << 8;
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@ -533,18 +558,18 @@ sword32 sword32_eq(sword32 a, sword32 b)
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a &= a << 2;
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a &= a << 1;
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/* return a >> 31; */
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return (sword32)SignExtend(a);
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return (sword32)SignExtend<31>(a);
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}
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/* sword32_gte returns 0xffffffff if a >= b and zero otherwise, where a and b are
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* both non-negative. */
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sword32 sword32_gte(sword32 a, sword32 b)
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{
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// Modified for SunCC. See comments for SignExtexnd function.
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// Modified for SunCC. See comments for CRYPTOPP_ASR_ASM.
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a -= b;
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/* a >= 0 iff a >= b. */
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/* return ~(a >> 31); */
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return ~(sword32)SignExtend(a);
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return ~(sword32)SignExtend<31>(a);
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}
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/* Take a fully reduced polynomial form number and contract it into a
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