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 (u16)((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
fld_const(FPU_REG const * c,int adj,u_char tag)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
fld1(int rc)73 static void fld1(int rc)
74 {
75 fld_const(&CONST_1, 0, TAG_Valid);
76 }
77
fldl2t(int rc)78 static void fldl2t(int rc)
79 {
80 fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid);
81 }
82
fldl2e(int rc)83 static void fldl2e(int rc)
84 {
85 fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
86 }
87
fldpi(int rc)88 static void fldpi(int rc)
89 {
90 fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
91 }
92
fldlg2(int rc)93 static void fldlg2(int rc)
94 {
95 fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
96 }
97
fldln2(int rc)98 static void fldln2(int rc)
99 {
100 fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
101 }
102
fldz(int rc)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
fconst(void)114 void fconst(void)
115 {
116 (constants_table[FPU_rm]) (control_word & CW_RC);
117 }
118