1 #include <../src/sys/classes/random/randomimpl.h> 2 3 typedef struct { 4 unsigned short seed[3]; 5 unsigned short mult[3]; 6 unsigned short add; 7 } PetscRandom_Rander48; 8 9 #define RANDER48_SEED_0 (0x330e) 10 #define RANDER48_SEED_1 (0xabcd) 11 #define RANDER48_SEED_2 (0x1234) 12 #define RANDER48_MULT_0 (0xe66d) 13 #define RANDER48_MULT_1 (0xdeec) 14 #define RANDER48_MULT_2 (0x0005) 15 #define RANDER48_ADD (0x000b) 16 17 static double _dorander48(PetscRandom_Rander48 *r48) 18 { 19 unsigned long accu; 20 unsigned short temp[2]; 21 22 accu = (unsigned long) r48->mult[0] * (unsigned long) r48->seed[0] + (unsigned long)r48->add; 23 temp[0] = (unsigned short) accu; /* lower 16 bits */ 24 accu >>= sizeof(unsigned short) * 8; 25 accu += (unsigned long) r48->mult[0] * (unsigned long) r48->seed[1] + (unsigned long) r48->mult[1] * (unsigned long) r48->seed[0]; 26 temp[1] = (unsigned short)accu; /* middle 16 bits */ 27 accu >>= sizeof(unsigned short) * 8; 28 accu += r48->mult[0] * r48->seed[2] + r48->mult[1] * r48->seed[1] + r48->mult[2] * r48->seed[0]; 29 r48->seed[0] = temp[0]; 30 r48->seed[1] = temp[1]; 31 r48->seed[2] = (unsigned short) accu; 32 return ldexp((double) r48->seed[0], -48) + ldexp((double) r48->seed[1], -32) + ldexp((double) r48->seed[2], -16); 33 } 34 35 static PetscErrorCode PetscRandomSeed_Rander48(PetscRandom r) 36 { 37 PetscRandom_Rander48 *r48 = (PetscRandom_Rander48*)r->data; 38 39 PetscFunctionBegin; 40 r48->seed[0] = RANDER48_SEED_0; 41 r48->seed[1] = (unsigned short) r->seed; 42 r48->seed[2] = (unsigned short) (r->seed >> 16); 43 r48->mult[0] = RANDER48_MULT_0; 44 r48->mult[1] = RANDER48_MULT_1; 45 r48->mult[2] = RANDER48_MULT_2; 46 r48->add = RANDER48_ADD; 47 PetscFunctionReturn(0); 48 } 49 50 static PetscErrorCode PetscRandomGetValue_Rander48(PetscRandom r, PetscScalar *val) 51 { 52 PetscRandom_Rander48 *r48 = (PetscRandom_Rander48*)r->data; 53 54 PetscFunctionBegin; 55 #if defined(PETSC_USE_COMPLEX) 56 if (r->iset) { 57 *val = PetscRealPart(r->low) + PetscImaginaryPart(r->low) * PETSC_i; 58 if (PetscRealPart(r->width)) { 59 *val += PetscRealPart(r->width)* _dorander48(r48); 60 } 61 if (PetscImaginaryPart(r->width)) { 62 *val += PetscImaginaryPart(r->width)* _dorander48(r48) * PETSC_i; 63 } 64 } else { 65 *val = _dorander48(r48) + _dorander48(r48)*PETSC_i; 66 } 67 #else 68 if (r->iset) *val = r->width * _dorander48(r48) + r->low; 69 else *val = _dorander48(r48); 70 #endif 71 PetscFunctionReturn(0); 72 } 73 74 static PetscErrorCode PetscRandomGetValueReal_Rander48(PetscRandom r, PetscReal *val) 75 { 76 PetscRandom_Rander48 *r48 = (PetscRandom_Rander48*)r->data; 77 78 PetscFunctionBegin; 79 #if defined(PETSC_USE_COMPLEX) 80 if (r->iset) *val = PetscRealPart(r->width)*_dorander48(r48) + PetscRealPart(r->low); 81 else *val = _dorander48(r48); 82 #else 83 if (r->iset) *val = r->width * _dorander48(r48) + r->low; 84 else *val = _dorander48(r48); 85 #endif 86 PetscFunctionReturn(0); 87 } 88 89 static PetscErrorCode PetscRandomDestroy_Rander48(PetscRandom r) 90 { 91 PetscErrorCode ierr; 92 93 PetscFunctionBegin; 94 ierr = PetscFree(r->data);CHKERRQ(ierr); 95 PetscFunctionReturn(0); 96 } 97 98 static struct _PetscRandomOps PetscRandomOps_Values = { 99 /* 0 */ 100 PetscRandomSeed_Rander48, 101 PetscRandomGetValue_Rander48, 102 PetscRandomGetValueReal_Rander48, 103 PetscRandomDestroy_Rander48, 104 /* 5 */ 105 0 106 }; 107 108 /*MC 109 PETSCRANDER48 - simple portable reimplementation of basic Unix drand48() random number generator that should generate the 110 exact same random numbers on any system. 111 112 Options Database Keys: 113 . -random_type <rand,rand48,rander48,sprng> 114 115 Notes: This is the default random number generate provided by PetscRandomCreate() if you do not set a particular implementation. 116 117 Each PetscRandom object created with this type has its own seed and its own history, so multiple PetscRandom objects of this type 118 will not interfer with random numbers generated by other objects. Each PETSc object of this type will produce the exact same set of 119 random numbers so if you wish different PetscObjects of this type set different seeds for each one after you create them with 120 PetscRandomSetSeed() followed by PetscRandomSeed(). 121 122 Level: beginner 123 124 .seealso: RandomCreate(), RandomSetType(), PETSCRAND, PETSCRAND48, PETSCRANDER48, PETSCSPRNG, PetscRandomSetSeed(), PetscRandomSeed() 125 M*/ 126 127 PETSC_EXTERN PetscErrorCode PetscRandomCreate_Rander48(PetscRandom r) 128 { 129 PetscErrorCode ierr; 130 PetscRandom_Rander48 *r48; 131 132 PetscFunctionBegin; 133 ierr = PetscNewLog(r,&r48);CHKERRQ(ierr); 134 /* r48 does not need to be initialized because PetscRandomSeed() is always called before use and sets the needed values */ 135 r->data = r48; 136 ierr = PetscMemcpy(r->ops, &PetscRandomOps_Values, sizeof(PetscRandomOps_Values));CHKERRQ(ierr); 137 ierr = PetscObjectChangeTypeName((PetscObject) r, PETSCRANDER48);CHKERRQ(ierr); 138 PetscFunctionReturn(0); 139 } 140