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