CoCalc -- reg

GitHub Repository: awilliam/linux-vfio
Path: blob/master/arch/x86/math-emu/reg_norm.S
¹⁰⁸¹⁷ views
1
/*---------------------------------------------------------------------------+
2
 |  reg_norm.S                                                               |
3
 |                                                                           |
4
 | Copyright (C) 1992,1993,1994,1995,1997                                    |
5
 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
6
 |                       Australia.  E-mail [email protected]               |
7
 |                                                                           |
8
 | Normalize the value in a FPU_REG.                                         |
9
 |                                                                           |
10
 | Call from C as:                                                           |
11
 |    int FPU_normalize(FPU_REG *n)                                          |
12
 |                                                                           |
13
 |    int FPU_normalize_nuo(FPU_REG *n)                                      |
14
 |                                                                           |
15
 |    Return value is the tag of the answer, or-ed with FPU_Exception if     |
16
 |    one was raised, or -1 on internal error.                               |
17
 |                                                                           |
18
 +---------------------------------------------------------------------------*/
19

20
#include "fpu_emu.h"
21

22

23
.text
24
ENTRY(FPU_normalize)
25
	pushl	%ebp
26
	movl	%esp,%ebp
27
	pushl	%ebx
28

29
	movl	PARAM1,%ebx
30

31
	movl	SIGH(%ebx),%edx
32
	movl	SIGL(%ebx),%eax
33

34
	orl	%edx,%edx	/* ms bits */
35
	js	L_done		/* Already normalized */
36
	jnz	L_shift_1	/* Shift left 1 - 31 bits */
37

38
	orl	%eax,%eax
39
	jz	L_zero		/* The contents are zero */
40

41
	movl	%eax,%edx
42
	xorl	%eax,%eax
43
	subw	$32,EXP(%ebx)	/* This can cause an underflow */
44

45
/* We need to shift left by 1 - 31 bits */
46
L_shift_1:
47
	bsrl	%edx,%ecx	/* get the required shift in %ecx */
48
	subl	$31,%ecx
49
	negl	%ecx
50
	shld	%cl,%eax,%edx
51
	shl	%cl,%eax
52
	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
53

54
	movl	%edx,SIGH(%ebx)
55
	movl	%eax,SIGL(%ebx)
56

57
L_done:
58
	cmpw	EXP_OVER,EXP(%ebx)
59
	jge	L_overflow
60

61
	cmpw	EXP_UNDER,EXP(%ebx)
62
	jle	L_underflow
63

64
L_exit_valid:
65
	movl	TAG_Valid,%eax
66

67
	/* Convert the exponent to 80x87 form. */
68
	addw	EXTENDED_Ebias,EXP(%ebx)
69
	andw	$0x7fff,EXP(%ebx)
70

71
L_exit:
72
	popl	%ebx
73
	leave
74
	ret
75

76

77
L_zero:
78
	movw	$0,EXP(%ebx)
79
	movl	TAG_Zero,%eax
80
	jmp	L_exit
81

82
L_underflow:
83
	/* Convert the exponent to 80x87 form. */
84
	addw	EXTENDED_Ebias,EXP(%ebx)
85
	push	%ebx
86
	call	arith_underflow
87
	pop	%ebx
88
	jmp	L_exit
89

90
L_overflow:
91
	/* Convert the exponent to 80x87 form. */
92
	addw	EXTENDED_Ebias,EXP(%ebx)
93
	push	%ebx
94
	call	arith_overflow
95
	pop	%ebx
96
	jmp	L_exit
97

98

99

100
/* Normalise without reporting underflow or overflow */
101
ENTRY(FPU_normalize_nuo)
102
	pushl	%ebp
103
	movl	%esp,%ebp
104
	pushl	%ebx
105

106
	movl	PARAM1,%ebx
107

108
	movl	SIGH(%ebx),%edx
109
	movl	SIGL(%ebx),%eax
110

111
	orl	%edx,%edx	/* ms bits */
112
	js	L_exit_nuo_valid	/* Already normalized */
113
	jnz	L_nuo_shift_1	/* Shift left 1 - 31 bits */
114

115
	orl	%eax,%eax
116
	jz	L_exit_nuo_zero		/* The contents are zero */
117

118
	movl	%eax,%edx
119
	xorl	%eax,%eax
120
	subw	$32,EXP(%ebx)	/* This can cause an underflow */
121

122
/* We need to shift left by 1 - 31 bits */
123
L_nuo_shift_1:
124
	bsrl	%edx,%ecx	/* get the required shift in %ecx */
125
	subl	$31,%ecx
126
	negl	%ecx
127
	shld	%cl,%eax,%edx
128
	shl	%cl,%eax
129
	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
130

131
	movl	%edx,SIGH(%ebx)
132
	movl	%eax,SIGL(%ebx)
133

134
L_exit_nuo_valid:
135
	movl	TAG_Valid,%eax
136

137
	popl	%ebx
138
	leave
139
	ret
140

141
L_exit_nuo_zero:
142
	movl	TAG_Zero,%eax
143
	movw	EXP_UNDER,EXP(%ebx)
144

145
	popl	%ebx
146
	leave
147
	ret
148

149
Product

Resources

Company
