Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / arch / x86 / math-emu / reg_u_add.S
1         .file   "reg_u_add.S"
2 /*---------------------------------------------------------------------------+
3  |  reg_u_add.S                                                              |
4  |                                                                           |
5  | Add two valid (TAG_Valid) FPU_REG numbers, of the same sign, and put the  |
6  |   result in a destination FPU_REG.                                        |
7  |                                                                           |
8  | Copyright (C) 1992,1993,1995,1997                                         |
9  |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
10  |                  E-mail   billm@suburbia.net                              |
11  |                                                                           |
12  | Call from C as:                                                           |
13  |   int  FPU_u_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,             |
14  |                                                int control_w)             |
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 /*
21  |    Kernel addition routine FPU_u_add(reg *arg1, reg *arg2, reg *answ).
22  |    Takes two valid reg f.p. numbers (TAG_Valid), which are
23  |    treated as unsigned numbers,
24  |    and returns their sum as a TAG_Valid or TAG_Special f.p. number.
25  |    The returned number is normalized.
26  |    Basic checks are performed if PARANOID is defined.
27  */
28
29 #include "exception.h"
30 #include "fpu_emu.h"
31 #include "control_w.h"
32
33 .text
34 ENTRY(FPU_u_add)
35         pushl   %ebp
36         movl    %esp,%ebp
37         pushl   %esi
38         pushl   %edi
39         pushl   %ebx
40
41         movl    PARAM1,%esi             /* source 1 */
42         movl    PARAM2,%edi             /* source 2 */
43
44         movl    PARAM6,%ecx
45         movl    %ecx,%edx
46         subl    PARAM7,%ecx                     /* exp1 - exp2 */
47         jge     L_arg1_larger
48
49         /* num1 is smaller */
50         movl    SIGL(%esi),%ebx
51         movl    SIGH(%esi),%eax
52
53         movl    %edi,%esi
54         movl    PARAM7,%edx
55         negw    %cx
56         jmp     L_accum_loaded
57
58 L_arg1_larger:
59         /* num1 has larger or equal exponent */
60         movl    SIGL(%edi),%ebx
61         movl    SIGH(%edi),%eax
62
63 L_accum_loaded:
64         movl    PARAM3,%edi             /* destination */
65         movw    %dx,EXP(%edi)           /* Copy exponent to destination */
66
67         xorl    %edx,%edx               /* clear the extension */
68
69 #ifdef PARANOID
70         testl   $0x80000000,%eax
71         je      L_bugged
72
73         testl   $0x80000000,SIGH(%esi)
74         je      L_bugged
75 #endif /* PARANOID */
76
77 /* The number to be shifted is in %eax:%ebx:%edx */
78         cmpw    $32,%cx         /* shrd only works for 0..31 bits */
79         jnc     L_more_than_31
80
81 /* less than 32 bits */
82         shrd    %cl,%ebx,%edx
83         shrd    %cl,%eax,%ebx
84         shr     %cl,%eax
85         jmp     L_shift_done
86
87 L_more_than_31:
88         cmpw    $64,%cx
89         jnc     L_more_than_63
90
91         subb    $32,%cl
92         jz      L_exactly_32
93
94         shrd    %cl,%eax,%edx
95         shr     %cl,%eax
96         orl     %ebx,%ebx
97         jz      L_more_31_no_low        /* none of the lowest bits is set */
98
99         orl     $1,%edx                 /* record the fact in the extension */
100
101 L_more_31_no_low:
102         movl    %eax,%ebx
103         xorl    %eax,%eax
104         jmp     L_shift_done
105
106 L_exactly_32:
107         movl    %ebx,%edx
108         movl    %eax,%ebx
109         xorl    %eax,%eax
110         jmp     L_shift_done
111
112 L_more_than_63:
113         cmpw    $65,%cx
114         jnc     L_more_than_64
115
116         movl    %eax,%edx
117         orl     %ebx,%ebx
118         jz      L_more_63_no_low
119
120         orl     $1,%edx
121         jmp     L_more_63_no_low
122
123 L_more_than_64:
124         movl    $1,%edx         /* The shifted nr always at least one '1' */
125
126 L_more_63_no_low:
127         xorl    %ebx,%ebx
128         xorl    %eax,%eax
129
130 L_shift_done:
131         /* Now do the addition */
132         addl    SIGL(%esi),%ebx
133         adcl    SIGH(%esi),%eax
134         jnc     L_round_the_result
135
136         /* Overflow, adjust the result */
137         rcrl    $1,%eax
138         rcrl    $1,%ebx
139         rcrl    $1,%edx
140         jnc     L_no_bit_lost
141
142         orl     $1,%edx
143
144 L_no_bit_lost:
145         incw    EXP(%edi)
146
147 L_round_the_result:
148         jmp     fpu_reg_round   /* Round the result */
149
150
151
152 #ifdef PARANOID
153 /* If we ever get here then we have problems! */
154 L_bugged:
155         pushl   EX_INTERNAL|0x201
156         call    EXCEPTION
157         pop     %ebx
158         movl    $-1,%eax
159         jmp     L_exit
160
161 L_exit:
162         popl    %ebx
163         popl    %edi
164         popl    %esi
165         leave
166         ret
167 #endif /* PARANOID */