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
22FPU_REG const CONST_1 = MAKE_REG(POS, 0, 0x00000000, 0x80000000);
23#if 0
24FPU_REG const CONST_2 = MAKE_REG(POS, 1, 0x00000000, 0x80000000);
25FPU_REG const CONST_HALF = MAKE_REG(POS, -1, 0x00000000, 0x80000000);
26#endif /*  0  */
27static FPU_REG const CONST_L2T = MAKE_REG(POS, 1, 0xcd1b8afe, 0xd49a784b);
28static FPU_REG const CONST_L2E = MAKE_REG(POS, 0, 0x5c17f0bc, 0xb8aa3b29);
29FPU_REG const CONST_PI = MAKE_REG(POS, 1, 0x2168c235, 0xc90fdaa2);
30FPU_REG const CONST_PI2 = MAKE_REG(POS, 0, 0x2168c235, 0xc90fdaa2);
31FPU_REG const CONST_PI4 = MAKE_REG(POS, -1, 0x2168c235, 0xc90fdaa2);
32static FPU_REG const CONST_LG2 = MAKE_REG(POS, -2, 0xfbcff799, 0x9a209a84);
33static 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. */
36FPU_REG const CONST_PI2extra = MAKE_REG(NEG, -66,
37					0xfc8f8cbb, 0xece675d1);
38
39/* Only the sign (and tag) is used in internal zeroes */
40FPU_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
44FPU_REG const CONST_SNAN = MAKE_REG(POS, EXP_OVER, 0x00000001, 0x80000000);
45 */
46/* This is the real indefinite QNaN */
47FPU_REG const CONST_QNaN = MAKE_REG(NEG, EXP_OVER, 0x00000000, 0xC0000000);
48
49/* Only the sign (and tag) is used in internal infinities */
50FPU_REG const CONST_INF = MAKE_REG(POS, EXP_OVER, 0x00000000, 0x80000000);
51
52static 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
73static void fld1(int rc)
74{
75	fld_const(&CONST_1, 0, TAG_Valid);
76}
77
78static void fldl2t(int rc)
79{
80	fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid);
81}
82
83static void fldl2e(int rc)
84{
85	fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
86}
87
88static void fldpi(int rc)
89{
90	fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
91}
92
93static void fldlg2(int rc)
94{
95	fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
96}
97
98static void fldln2(int rc)
99{
100	fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
101}
102
103static void fldz(int rc)
104{
105	fld_const(&CONST_Z, 0, TAG_Zero);
106}
107
108typedef void (*FUNC_RC) (int);
109
110static FUNC_RC constants_table[] = {
111	fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC) FPU_illegal
112};
113
114void fconst(void)
115{
116	(constants_table[FPU_rm]) (control_word & CW_RC);
117}
118