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