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65 lines
1.3 KiB
ArmAsm
65 lines
1.3 KiB
ArmAsm
#include "textflag.h"
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// Digits of 3^238 - 1
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#define THREE238M1_0 $0xedcd718a828384f8
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#define THREE238M1_1 $0x733b35bfd4427a14
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#define THREE238M1_2 $0xf88229cf94d7cf38
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#define THREE238M1_3 $0x63c56c990c7c2ad6
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#define THREE238M1_4 $0xb858a87e8f4222c7
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#define THREE238M1_5 $0x254c9c6b525eaf5
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TEXT ·checkLessThanThree238(SB), NOSPLIT, $0-16
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MOVQ scalar+0(FP), SI
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MOVQ result+8(FP), DI
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XORQ AX, AX
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// Set [R10,...,R15] = 3^238
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MOVQ THREE238M1_0, R10
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MOVQ THREE238M1_1, R11
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MOVQ THREE238M1_2, R12
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MOVQ THREE238M1_3, R13
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MOVQ THREE238M1_4, R14
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MOVQ THREE238M1_5, R15
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// Set [R10,...,R15] = 3^238 - scalar
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SUBQ (SI), R10
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SBBQ (8)(SI), R11
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SBBQ (16)(SI), R12
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SBBQ (24)(SI), R13
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SBBQ (32)(SI), R14
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SBBQ (40)(SI), R15
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// Save borrow flag indicating 3^238 - scalar < 0 as a mask in AX (eax)
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SBBL $0, AX
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MOVL AX, (DI)
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RET
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TEXT ·multiplyByThree(SB), NOSPLIT, $0-8
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MOVQ scalar+0(FP), SI
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// Set [R10,...,R15] = scalar
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MOVQ (SI), R10
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MOVQ (8)(SI), R11
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MOVQ (16)(SI), R12
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MOVQ (24)(SI), R13
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MOVQ (32)(SI), R14
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MOVQ (40)(SI), R15
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// Add scalar twice to compute 3*scalar
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ADDQ R10, (SI)
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ADCQ R11, (8)(SI)
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ADCQ R12, (16)(SI)
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ADCQ R13, (24)(SI)
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ADCQ R14, (32)(SI)
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ADCQ R15, (40)(SI)
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ADDQ R10, (SI)
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ADCQ R11, (8)(SI)
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ADCQ R12, (16)(SI)
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ADCQ R13, (24)(SI)
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ADCQ R14, (32)(SI)
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ADCQ R15, (40)(SI)
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RET
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