1 /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
2
3 #include <precomp.h>
4 #include <float.h>
5
6 #define X87_CW_IM (1<<0) /* Invalid operation mask */
7 #define X87_CW_DM (1<<1) /* Denormal operand mask */
8 #define X87_CW_ZM (1<<2) /* Zero divide mask */
9 #define X87_CW_OM (1<<3) /* Overflow mask */
10 #define X87_CW_UM (1<<4) /* Underflow mask */
11 #define X87_CW_PM (1<<5) /* Precision mask */
12
13 #define X87_CW_PC_MASK (3<<8) /* precision control mask */
14 #define X87_CW_PC24 (0<<8) /* 24 bit precision */
15 #define X87_CW_PC53 (2<<8) /* 53 bit precision */
16 #define X87_CW_PC64 (3<<8) /* 64 bit precision */
17
18 #define X87_CW_RC_MASK (3<<10) /* rounding control mask */
19 #define X87_CW_RC_NEAREST (0<<10) /* round to nearest */
20 #define X87_CW_RC_DOWN (1<<10) /* round down */
21 #define X87_CW_RC_UP (2<<10) /* round up */
22 #define X87_CW_RC_ZERO (3<<10) /* round toward zero (chop) */
23
24 #define X87_CW_IC (1<<12) /* infinity control flag */
25
26 #ifdef _M_AMD64
27 unsigned int __getfpcw87(void);
28 void __setfpcw87(unsigned int);
29 #endif
30
31 /*
32 * @implemented
33 */
34
_controlfp(unsigned int newval,unsigned int mask)35 unsigned int CDECL _controlfp(unsigned int newval, unsigned int mask)
36 {
37 return _control87( newval, mask & ~_EM_DENORMAL );
38 }
39
40 /*********************************************************************
41 * _control87 (MSVCRT.@)
42 */
_control87(unsigned int newval,unsigned int mask)43 unsigned int CDECL _control87(unsigned int newval, unsigned int mask)
44 {
45 unsigned short fpword = 0;
46 unsigned int flags = 0;
47
48 TRACE("(%08x, %08x): Called\n", newval, mask);
49
50 /* Get fp control word */
51 #ifdef _M_AMD64
52 fpword = __getfpcw87();
53 #elif defined(__GNUC__)
54 __asm__ __volatile__( "fstcw %0" : "=m" (fpword) : );
55 #else
56 __asm fstcw [fpword];
57 #endif
58
59 TRACE("Control word before : %08x\n", fpword);
60
61 /* Convert into mask constants */
62 if (fpword & 0x1) flags |= _EM_INVALID;
63 if (fpword & 0x2) flags |= _EM_DENORMAL;
64 if (fpword & 0x4) flags |= _EM_ZERODIVIDE;
65 if (fpword & 0x8) flags |= _EM_OVERFLOW;
66 if (fpword & 0x10) flags |= _EM_UNDERFLOW;
67 if (fpword & 0x20) flags |= _EM_INEXACT;
68 switch(fpword & 0xC00) {
69 case 0xC00: flags |= _RC_UP|_RC_DOWN; break;
70 case 0x800: flags |= _RC_UP; break;
71 case 0x400: flags |= _RC_DOWN; break;
72 }
73 switch(fpword & 0x300) {
74 case 0x0: flags |= _PC_24; break;
75 case 0x200: flags |= _PC_53; break;
76 case 0x300: flags |= _PC_64; break;
77 }
78 if (fpword & 0x1000) flags |= _IC_AFFINE;
79
80 /* Mask with parameters */
81 flags = (flags & ~mask) | (newval & mask);
82
83 /* Convert (masked) value back to fp word */
84 fpword = 0;
85 if (flags & _EM_INVALID) fpword |= 0x1;
86 if (flags & _EM_DENORMAL) fpword |= 0x2;
87 if (flags & _EM_ZERODIVIDE) fpword |= 0x4;
88 if (flags & _EM_OVERFLOW) fpword |= 0x8;
89 if (flags & _EM_UNDERFLOW) fpword |= 0x10;
90 if (flags & _EM_INEXACT) fpword |= 0x20;
91 switch(flags & (_RC_UP | _RC_DOWN)) {
92 case _RC_UP|_RC_DOWN: fpword |= 0xC00; break;
93 case _RC_UP: fpword |= 0x800; break;
94 case _RC_DOWN: fpword |= 0x400; break;
95 }
96 switch (flags & (_PC_24 | _PC_53)) {
97 case _PC_64: fpword |= 0x300; break;
98 case _PC_53: fpword |= 0x200; break;
99 case _PC_24: fpword |= 0x0; break;
100 }
101 if (flags & _IC_AFFINE) fpword |= 0x1000;
102
103 TRACE("Control word after : %08x\n", fpword);
104
105 /* Put fp control word */
106 #ifdef _M_AMD64
107 __setfpcw87(fpword);
108 #elif defined(__GNUC__)
109 __asm__ __volatile__( "fldcw %0" : : "m" (fpword) );
110 #else
111 __asm fldcw [fpword];
112 #endif
113
114 return flags;
115 }
116