1 #include <petsc/private/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 PetscFunctionBegin; 92 PetscCall(PetscFree(r->data)); 93 PetscFunctionReturn(0); 94 } 95 96 static struct _PetscRandomOps PetscRandomOps_Values = { 97 PetscDesignatedInitializer(seed,PetscRandomSeed_Rander48), 98 PetscDesignatedInitializer(getvalue,PetscRandomGetValue_Rander48), 99 PetscDesignatedInitializer(getvaluereal,PetscRandomGetValueReal_Rander48), 100 PetscDesignatedInitializer(getvalues,NULL), 101 PetscDesignatedInitializer(getvaluesreal,NULL), 102 PetscDesignatedInitializer(destroy,PetscRandomDestroy_Rander48), 103 }; 104 105 /*MC 106 PETSCRANDER48 - simple portable reimplementation of basic Unix drand48() random number generator that should generate the 107 exact same random numbers on any system. 108 109 Options Database Keys: 110 . -random_type <rand,rand48,rander48,sprng> 111 112 Notes: 113 This is the default random number generate provided by PetscRandomCreate() if you do not set a particular implementation. 114 115 Each PetscRandom object created with this type has its own seed and its own history, so multiple PetscRandom objects of this type 116 will not interfer with random numbers generated by other objects. Each PETSc object of this type will produce the exact same set of 117 random numbers so if you wish different PetscObjects of this type set different seeds for each one after you create them with 118 PetscRandomSetSeed() followed by PetscRandomSeed(). 119 120 Level: beginner 121 122 .seealso: PetscRandomCreate(), PetscRandomSetType(), PETSCRAND, PETSCRAND48, PETSCRANDER48, PETSCSPRNG, PetscRandomSetSeed(), PetscRandomSeed() 123 M*/ 124 125 PETSC_EXTERN PetscErrorCode PetscRandomCreate_Rander48(PetscRandom r) 126 { 127 PetscRandom_Rander48 *r48; 128 129 PetscFunctionBegin; 130 PetscCall(PetscNewLog(r,&r48)); 131 /* r48 does not need to be initialized because PetscRandomSeed() is always called before use and sets the needed values */ 132 r->data = r48; 133 PetscCall(PetscMemcpy(r->ops, &PetscRandomOps_Values, sizeof(PetscRandomOps_Values))); 134 PetscCall(PetscObjectChangeTypeName((PetscObject) r, PETSCRANDER48)); 135 PetscFunctionReturn(0); 136 } 137