1/* SPDX-License-Identifier: GPL-2.0 */
2	.file	"reg_u_add.S"
3/*---------------------------------------------------------------------------+
4 |  reg_u_add.S                                                              |
5 |                                                                           |
6 | Add two valid (TAG_Valid) FPU_REG numbers, of the same sign, and put the  |
7 |   result in a destination FPU_REG.                                        |
8 |                                                                           |
9 | Copyright (C) 1992,1993,1995,1997                                         |
10 |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
11 |                  E-mail   billm@suburbia.net                              |
12 |                                                                           |
13 | Call from C as:                                                           |
14 |   int  FPU_u_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,             |
15 |                                                int control_w)             |
16 |    Return value is the tag of the answer, or-ed with FPU_Exception if     |
17 |    one was raised, or -1 on internal error.                               |
18 |                                                                           |
19 +---------------------------------------------------------------------------*/
20
21/*
22 |    Kernel addition routine FPU_u_add(reg *arg1, reg *arg2, reg *answ).
23 |    Takes two valid reg f.p. numbers (TAG_Valid), which are
24 |    treated as unsigned numbers,
25 |    and returns their sum as a TAG_Valid or TAG_Special f.p. number.
26 |    The returned number is normalized.
27 |    Basic checks are performed if PARANOID is defined.
28 */
29
30#include "exception.h"
31#include "fpu_emu.h"
32#include "control_w.h"
33
34.text
35SYM_FUNC_START(FPU_u_add)
36	pushl	%ebp
37	movl	%esp,%ebp
38	pushl	%esi
39	pushl	%edi
40	pushl	%ebx
41
42	movl	PARAM1,%esi		/* source 1 */
43	movl	PARAM2,%edi		/* source 2 */
44
45	movl	PARAM6,%ecx
46	movl	%ecx,%edx
47	subl	PARAM7,%ecx			/* exp1 - exp2 */
48	jge	L_arg1_larger
49
50	/* num1 is smaller */
51	movl	SIGL(%esi),%ebx
52	movl	SIGH(%esi),%eax
53
54	movl	%edi,%esi
55	movl	PARAM7,%edx
56	negw	%cx
57	jmp	L_accum_loaded
58
59L_arg1_larger:
60	/* num1 has larger or equal exponent */
61	movl	SIGL(%edi),%ebx
62	movl	SIGH(%edi),%eax
63
64L_accum_loaded:
65	movl	PARAM3,%edi		/* destination */
66	movw	%dx,EXP(%edi)		/* Copy exponent to destination */
67
68	xorl	%edx,%edx		/* clear the extension */
69
70#ifdef PARANOID
71	testl	$0x80000000,%eax
72	je	L_bugged
73
74	testl	$0x80000000,SIGH(%esi)
75	je	L_bugged
76#endif /* PARANOID */
77
78/* The number to be shifted is in %eax:%ebx:%edx */
79	cmpw	$32,%cx		/* shrd only works for 0..31 bits */
80	jnc	L_more_than_31
81
82/* less than 32 bits */
83	shrd	%cl,%ebx,%edx
84	shrd	%cl,%eax,%ebx
85	shr	%cl,%eax
86	jmp	L_shift_done
87
88L_more_than_31:
89	cmpw	$64,%cx
90	jnc	L_more_than_63
91
92	subb	$32,%cl
93	jz	L_exactly_32
94
95	shrd	%cl,%eax,%edx
96	shr	%cl,%eax
97	orl	%ebx,%ebx
98	jz	L_more_31_no_low	/* none of the lowest bits is set */
99
100	orl	$1,%edx			/* record the fact in the extension */
101
102L_more_31_no_low:
103	movl	%eax,%ebx
104	xorl	%eax,%eax
105	jmp	L_shift_done
106
107L_exactly_32:
108	movl	%ebx,%edx
109	movl	%eax,%ebx
110	xorl	%eax,%eax
111	jmp	L_shift_done
112
113L_more_than_63:
114	cmpw	$65,%cx
115	jnc	L_more_than_64
116
117	movl	%eax,%edx
118	orl	%ebx,%ebx
119	jz	L_more_63_no_low
120
121	orl	$1,%edx
122	jmp	L_more_63_no_low
123
124L_more_than_64:
125	movl	$1,%edx		/* The shifted nr always at least one '1' */
126
127L_more_63_no_low:
128	xorl	%ebx,%ebx
129	xorl	%eax,%eax
130
131L_shift_done:
132	/* Now do the addition */
133	addl	SIGL(%esi),%ebx
134	adcl	SIGH(%esi),%eax
135	jnc	L_round_the_result
136
137	/* Overflow, adjust the result */
138	rcrl	$1,%eax
139	rcrl	$1,%ebx
140	rcrl	$1,%edx
141	jnc	L_no_bit_lost
142
143	orl	$1,%edx
144
145L_no_bit_lost:
146	incw	EXP(%edi)
147
148L_round_the_result:
149	jmp	fpu_reg_round	/* Round the result */
150
151
152
153#ifdef PARANOID
154/* If we ever get here then we have problems! */
155L_bugged:
156	pushl	EX_INTERNAL|0x201
157	call	EXCEPTION
158	pop	%ebx
159	movl	$-1,%eax
160	jmp	L_exit
161
162L_exit:
163	popl	%ebx
164	popl	%edi
165	popl	%esi
166	leave
167	ret
168#endif /* PARANOID */
169SYM_FUNC_END(FPU_u_add)
170