Botan  1.10.9
mp_asm.h
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1 /*
2 * MPI Multiply-Add Core
3 * (C) 1999-2007 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7 
8 #ifndef BOTAN_MP_MADD_H__
9 #define BOTAN_MP_MADD_H__
10 
11 #include <botan/mp_types.h>
12 
13 namespace Botan {
14 
15 #if (BOTAN_MP_WORD_BITS != 64)
16  #error The mp_asm64 module requires that BOTAN_MP_WORD_BITS == 64
17 #endif
18 
19 #if defined(BOTAN_TARGET_ARCH_IS_ALPHA)
20 
21 #define BOTAN_WORD_MUL(a,b,z1,z0) do { \
22  asm("umulh %1,%2,%0" : "=r" (z0) : "r" (a), "r" (b)); \
23  z1 = a * b; \
24 } while(0);
25 
26 #elif defined(BOTAN_TARGET_ARCH_IS_IA64)
27 
28 #define BOTAN_WORD_MUL(a,b,z1,z0) do { \
29  asm("xmpy.hu %0=%1,%2" : "=f" (z0) : "f" (a), "f" (b)); \
30  z1 = a * b; \
31 } while(0);
32 
33 #elif defined(BOTAN_TARGET_ARCH_IS_PPC64)
34 
35 #define BOTAN_WORD_MUL(a,b,z1,z0) do { \
36  asm("mulhdu %0,%1,%2" : "=r" (z0) : "r" (a), "r" (b) : "cc"); \
37  z1 = a * b; \
38 } while(0);
39 
40 #elif defined(BOTAN_TARGET_ARCH_IS_MIPS64)
41 
42 #define BOTAN_WORD_MUL(a,b,z1,z0) do { \
43  typedef unsigned int uint128_t __attribute__((mode(TI))); \
44  uint128_t r = (uint128_t)a * b; \
45  z0 = (r >> 64) & 0xFFFFFFFFFFFFFFFF; \
46  z1 = (r ) & 0xFFFFFFFFFFFFFFFF; \
47 } while(0);
48 
49 #else
50 
51 // Do a 64x64->128 multiply using four 64x64->64 multiplies
52 // plus some adds and shifts. Last resort for CPUs like UltraSPARC,
53 // with 64-bit registers/ALU, but no 64x64->128 multiply.
54 inline void bigint_2word_mul(word a, word b, word* z1, word* z0)
55  {
56  const size_t MP_HWORD_BITS = BOTAN_MP_WORD_BITS / 2;
57  const word MP_HWORD_MASK = ((word)1 << MP_HWORD_BITS) - 1;
58 
59  const word a_hi = (a >> MP_HWORD_BITS);
60  const word a_lo = (a & MP_HWORD_MASK);
61  const word b_hi = (b >> MP_HWORD_BITS);
62  const word b_lo = (b & MP_HWORD_MASK);
63 
64  word x0 = a_hi * b_hi;
65  word x1 = a_lo * b_hi;
66  word x2 = a_hi * b_lo;
67  word x3 = a_lo * b_lo;
68 
69  x2 += x3 >> (MP_HWORD_BITS);
70  x2 += x1;
71 
72  if(x2 < x1) // timing channel
73  x0 += ((word)1 << MP_HWORD_BITS);
74 
75  *z0 = x0 + (x2 >> MP_HWORD_BITS);
76  *z1 = ((x2 & MP_HWORD_MASK) << MP_HWORD_BITS) + (x3 & MP_HWORD_MASK);
77  }
78 
79 #define BOTAN_WORD_MUL(a,b,z1,z0) bigint_2word_mul(a, b, &z1, &z0)
80 
81 #endif
82 
83 /*
84 * Word Multiply/Add
85 */
86 inline word word_madd2(word a, word b, word* c)
87  {
88  word z0 = 0, z1 = 0;
89 
90  BOTAN_WORD_MUL(a, b, z1, z0);
91 
92  z1 += *c;
93  z0 += (z1 < *c);
94 
95  *c = z0;
96  return z1;
97  }
98 
99 /*
100 * Word Multiply/Add
101 */
102 inline word word_madd3(word a, word b, word c, word* d)
103  {
104  word z0 = 0, z1 = 0;
105 
106  BOTAN_WORD_MUL(a, b, z1, z0);
107 
108  z1 += c;
109  z0 += (z1 < c);
110 
111  z1 += *d;
112  z0 += (z1 < *d);
113 
114  *d = z0;
115  return z1;
116  }
117 
118 }
119 
120 #endif
void bigint_2word_mul(word a, word b, word *z1, word *z0)
Definition: mp_asm.h:54
word word_madd3(word a, word b, word c, word *d)
Definition: mp_asm.h:102
#define BOTAN_WORD_MUL(a, b, z1, z0)
Definition: mp_asm.h:79
word word_madd2(word a, word b, word *c)
Definition: mp_asm.h:86