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
149