1 // SPDX-License-Identifier: GPL-2.0 2 /*---------------------------------------------------------------------------+ 3 | reg_constant.c | 4 | | 5 | All of the constant FPU_REGs | 6 | | 7 | Copyright (C) 1992,1993,1994,1997 | 8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | 9 | Australia. E-mail billm@suburbia.net | 10 | | 11 | | 12 +---------------------------------------------------------------------------*/ 13 14 #include "fpu_system.h" 15 #include "fpu_emu.h" 16 #include "status_w.h" 17 #include "reg_constant.h" 18 #include "control_w.h" 19 20 #define MAKE_REG(s, e, l, h) { l, h, \ 21 (u16)((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 static void fld_const(FPU_REG const * c, int adj, u_char tag) 54 { 55 FPU_REG *st_new_ptr; 56 57 if (STACK_OVERFLOW) { 58 FPU_stack_overflow(); 59 return; 60 } 61 push(); 62 reg_copy(c, st_new_ptr); 63 st_new_ptr->sigl += adj; /* For all our fldxxx constants, we don't need to 64 borrow or carry. */ 65 FPU_settag0(tag); 66 clear_C1(); 67 } 68 69 /* A fast way to find out whether x is one of RC_DOWN or RC_CHOP 70 (and not one of RC_RND or RC_UP). 71 */ 72 #define DOWN_OR_CHOP(x) (x & RC_DOWN) 73 74 static void fld1(int rc) 75 { 76 fld_const(&CONST_1, 0, TAG_Valid); 77 } 78 79 static void fldl2t(int rc) 80 { 81 fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid); 82 } 83 84 static void fldl2e(int rc) 85 { 86 fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 87 } 88 89 static void fldpi(int rc) 90 { 91 fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 92 } 93 94 static void fldlg2(int rc) 95 { 96 fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 97 } 98 99 static void fldln2(int rc) 100 { 101 fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid); 102 } 103 104 static void fldz(int rc) 105 { 106 fld_const(&CONST_Z, 0, TAG_Zero); 107 } 108 109 typedef void (*FUNC_RC) (int); 110 111 static FUNC_RC constants_table[] = { 112 fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC) FPU_illegal 113 }; 114 115 void fconst(void) 116 { 117 (constants_table[FPU_rm]) (control_word & CW_RC); 118 } 119