1 /*---------------------------------------------------------------------------+ 2 | reg_constant.c | 3 | | 4 | All of the constant FPU_REGs | 5 | | 6 | Copyright (C) 1992,1993,1994,1997 | 7 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | 8 | Australia. E-mail billm@suburbia.net | 9 | | 10 | | 11 +---------------------------------------------------------------------------*/ 12 13 #include "fpu_system.h" 14 #include "fpu_emu.h" 15 #include "status_w.h" 16 #include "reg_constant.h" 17 #include "control_w.h" 18 19 20 #define MAKE_REG(s,e,l,h) { l, h, \ 21 ((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) } 22 23 FPU_REG const CONST_1 = MAKE_REG(POS, 0, 0x00000000, 0x80000000); 24 #if 0 25 FPU_REG const CONST_2 = MAKE_REG(POS, 1, 0x00000000, 0x80000000); 26 FPU_REG const CONST_HALF = MAKE_REG(POS, -1, 0x00000000, 0x80000000); 27 #endif /* 0 */ 28 static FPU_REG const CONST_L2T = MAKE_REG(POS, 1, 0xcd1b8afe, 0xd49a784b); 29 static FPU_REG const CONST_L2E = MAKE_REG(POS, 0, 0x5c17f0bc, 0xb8aa3b29); 30 FPU_REG const CONST_PI = MAKE_REG(POS, 1, 0x2168c235, 0xc90fdaa2); 31 FPU_REG const CONST_PI2 = MAKE_REG(POS, 0, 0x2168c235, 0xc90fdaa2); 32 FPU_REG const CONST_PI4 = MAKE_REG(POS, -1, 0x2168c235, 0xc90fdaa2); 33 static FPU_REG const CONST_LG2 = MAKE_REG(POS, -2, 0xfbcff799, 0x9a209a84); 34 static FPU_REG const CONST_LN2 = MAKE_REG(POS, -1, 0xd1cf79ac, 0xb17217f7); 35 36 /* Extra bits to take pi/2 to more than 128 bits precision. */ 37 FPU_REG const CONST_PI2extra = MAKE_REG(NEG, -66, 38 0xfc8f8cbb, 0xece675d1); 39 40 /* Only the sign (and tag) is used in internal zeroes */ 41 FPU_REG const CONST_Z = MAKE_REG(POS, EXP_UNDER, 0x0, 0x0); 42 43 /* Only the sign and significand (and tag) are used in internal NaNs */ 44 /* The 80486 never generates one of these 45 FPU_REG const CONST_SNAN = MAKE_REG(POS, EXP_OVER, 0x00000001, 0x80000000); 46 */ 47 /* This is the real indefinite QNaN */ 48 FPU_REG const CONST_QNaN = MAKE_REG(NEG, EXP_OVER, 0x00000000, 0xC0000000); 49 50 /* Only the sign (and tag) is used in internal infinities */ 51 FPU_REG const CONST_INF = MAKE_REG(POS, EXP_OVER, 0x00000000, 0x80000000); 52 53 54 static void fld_const(FPU_REG const *c, int adj, u_char tag) 55 { 56 FPU_REG *st_new_ptr; 57 58 if ( STACK_OVERFLOW ) 59 { 60 FPU_stack_overflow(); 61 return; 62 } 63 push(); 64 reg_copy(c, st_new_ptr); 65 st_new_ptr->sigl += adj; /* For all our fldxxx constants, we don't need to 66 borrow or carry. */ 67 FPU_settag0(tag); 68 clear_C1(); 69 } 70 71 /* A fast way to find out whether x is one of RC_DOWN or RC_CHOP 72 (and not one of RC_RND or RC_UP). 73 */ 74 #define DOWN_OR_CHOP(x) (x & RC_DOWN) 75 76 static void fld1(int rc) 77 { 78 fld_const(&CONST_1, 0, TAG_Valid); 79 } 80 81 static void fldl2t(int rc) 82 { 83 fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid); 84 } 85 86 static void fldl2e(int rc) 87 { 88 fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 89 } 90 91 static void fldpi(int rc) 92 { 93 fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 94 } 95 96 static void fldlg2(int rc) 97 { 98 fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 99 } 100 101 static void fldln2(int rc) 102 { 103 fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 104 } 105 106 static void fldz(int rc) 107 { 108 fld_const(&CONST_Z, 0, TAG_Zero); 109 } 110 111 typedef void (*FUNC_RC)(int); 112 113 static FUNC_RC constants_table[] = { 114 fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC)FPU_illegal 115 }; 116 117 void fconst(void) 118 { 119 (constants_table[FPU_rm])(control_word & CW_RC); 120 } 121