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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/math-emu/reg_u_mul.S
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/i386/math-emu/reg_u_mul.S')
-rw-r--r--arch/i386/math-emu/reg_u_mul.S148
1 files changed, 148 insertions, 0 deletions
diff --git a/arch/i386/math-emu/reg_u_mul.S b/arch/i386/math-emu/reg_u_mul.S
new file mode 100644
index 000000000000..973f12af97df
--- /dev/null
+++ b/arch/i386/math-emu/reg_u_mul.S
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1 .file "reg_u_mul.S"
2/*---------------------------------------------------------------------------+
3 | reg_u_mul.S |
4 | |
5 | Core multiplication routine |
6 | |
7 | Copyright (C) 1992,1993,1995,1997 |
8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
9 | E-mail billm@suburbia.net |
10 | |
11 | |
12 +---------------------------------------------------------------------------*/
13
14/*---------------------------------------------------------------------------+
15 | Basic multiplication routine. |
16 | Does not check the resulting exponent for overflow/underflow |
17 | |
18 | FPU_u_mul(FPU_REG *a, FPU_REG *b, FPU_REG *c, unsigned int cw); |
19 | |
20 | Internal working is at approx 128 bits. |
21 | Result is rounded to nearest 53 or 64 bits, using "nearest or even". |
22 +---------------------------------------------------------------------------*/
23
24#include "exception.h"
25#include "fpu_emu.h"
26#include "control_w.h"
27
28
29
30#ifndef NON_REENTRANT_FPU
31/* Local storage on the stack: */
32#define FPU_accum_0 -4(%ebp) /* ms word */
33#define FPU_accum_1 -8(%ebp)
34
35#else
36/* Local storage in a static area: */
37.data
38 .align 4,0
39FPU_accum_0:
40 .long 0
41FPU_accum_1:
42 .long 0
43#endif /* NON_REENTRANT_FPU */
44
45
46.text
47ENTRY(FPU_u_mul)
48 pushl %ebp
49 movl %esp,%ebp
50#ifndef NON_REENTRANT_FPU
51 subl $8,%esp
52#endif /* NON_REENTRANT_FPU */
53
54 pushl %esi
55 pushl %edi
56 pushl %ebx
57
58 movl PARAM1,%esi
59 movl PARAM2,%edi
60
61#ifdef PARANOID
62 testl $0x80000000,SIGH(%esi)
63 jz L_bugged
64 testl $0x80000000,SIGH(%edi)
65 jz L_bugged
66#endif /* PARANOID */
67
68 xorl %ecx,%ecx
69 xorl %ebx,%ebx
70
71 movl SIGL(%esi),%eax
72 mull SIGL(%edi)
73 movl %eax,FPU_accum_0
74 movl %edx,FPU_accum_1
75
76 movl SIGL(%esi),%eax
77 mull SIGH(%edi)
78 addl %eax,FPU_accum_1
79 adcl %edx,%ebx
80/* adcl $0,%ecx // overflow here is not possible */
81
82 movl SIGH(%esi),%eax
83 mull SIGL(%edi)
84 addl %eax,FPU_accum_1
85 adcl %edx,%ebx
86 adcl $0,%ecx
87
88 movl SIGH(%esi),%eax
89 mull SIGH(%edi)
90 addl %eax,%ebx
91 adcl %edx,%ecx
92
93 /* Get the sum of the exponents. */
94 movl PARAM6,%eax
95 subl EXP_BIAS-1,%eax
96
97 /* Two denormals can cause an exponent underflow */
98 cmpl EXP_WAY_UNDER,%eax
99 jg Exp_not_underflow
100
101 /* Set to a really low value allow correct handling */
102 movl EXP_WAY_UNDER,%eax
103
104Exp_not_underflow:
105
106/* Have now finished with the sources */
107 movl PARAM3,%edi /* Point to the destination */
108 movw %ax,EXP(%edi)
109
110/* Now make sure that the result is normalized */
111 testl $0x80000000,%ecx
112 jnz LResult_Normalised
113
114 /* Normalize by shifting left one bit */
115 shll $1,FPU_accum_0
116 rcll $1,FPU_accum_1
117 rcll $1,%ebx
118 rcll $1,%ecx
119 decw EXP(%edi)
120
121LResult_Normalised:
122 movl FPU_accum_0,%eax
123 movl FPU_accum_1,%edx
124 orl %eax,%eax
125 jz L_extent_zero
126
127 orl $1,%edx
128
129L_extent_zero:
130 movl %ecx,%eax
131 jmp fpu_reg_round
132
133
134#ifdef PARANOID
135L_bugged:
136 pushl EX_INTERNAL|0x205
137 call EXCEPTION
138 pop %ebx
139 jmp L_exit
140
141L_exit:
142 popl %ebx
143 popl %edi
144 popl %esi
145 leave
146 ret
147#endif /* PARANOID */
148