drivers/FPU-emu/reg_u

/* */
   1         .file   "reg_u_add.S"
   2 /*---------------------------------------------------------------------------+
   3  |  reg_u_add.S                                                              |
   4  |                                                                           |
   5  | Add two valid (TW_Valid) FPU_REG numbers, of the same sign, and put the   |
   6  |   result in a destination FPU_REG.                                        |
   7  |                                                                           |
   8  | Copyright (C) 1992,1993                                                   |
   9  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
  10  |                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au    |
  11  |                                                                           |
  12  | Call from C as:                                                           |
  13  |   void reg_u_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,             |
  14  |                                                int control_w)             |
  15  |                                                                           |
  16  +---------------------------------------------------------------------------*/
  17 
  18 /*
  19  |    Kernel addition routine reg_u_add(reg *arg1, reg *arg2, reg *answ).
  20  |    Takes two valid reg f.p. numbers (TW_Valid), which are
  21  |    treated as unsigned numbers,
  22  |    and returns their sum as a TW_Valid or TW_S f.p. number.
  23  |    The returned number is normalized.
  24  |    Basic checks are performed if PARANOID is defined.
  25  */
  26 
  27 #include "exception.h"
  28 #include "fpu_asm.h"
  29 #include "control_w.h"
  30 
  31 .text
  32         .align 2,144
  33 .globl _reg_u_add
  34 _reg_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 #ifdef DENORM_OPERAND
  45         cmpl    EXP_UNDER,EXP(%esi)
  46         jg      xOp1_not_denorm
  47 
  48         call    _denormal_operand
  49         orl     %eax,%eax
  50         jnz     fpu_Arith_exit
  51 
  52 xOp1_not_denorm:
  53         cmpl    EXP_UNDER,EXP(%edi)
  54         jg      xOp2_not_denorm
  55 
  56         call    _denormal_operand
  57         orl     %eax,%eax
  58         jnz     fpu_Arith_exit
  59 
  60 xOp2_not_denorm:
  61 #endif DENORM_OPERAND
  62 
  63         movl    EXP(%esi),%ecx
  64         subl    EXP(%edi),%ecx          /* exp1 - exp2 */
  65         jge     L_arg1_larger
  66 
  67         /* num1 is smaller */
  68         movl    SIGL(%esi),%ebx
  69         movl    SIGH(%esi),%eax
  70 
  71         movl    %edi,%esi
  72         negw    %cx
  73         jmp     L_accum_loaded
  74 
  75 L_arg1_larger:
  76         /* num1 has larger or equal exponent */
  77         movl    SIGL(%edi),%ebx
  78         movl    SIGH(%edi),%eax
  79 
  80 L_accum_loaded:
  81         movl    PARAM3,%edi             /* destination */
  82 /*      movb    SIGN(%esi),%dl
  83         movb    %dl,SIGN(%edi) */       /* Copy the sign from the first arg */
  84 
  85 
  86         movl    EXP(%esi),%edx
  87         movl    %edx,EXP(%edi)          /* Copy exponent to destination */
  88 
  89         xorl    %edx,%edx               /* clear the extension */
  90 
  91 #ifdef PARANOID
  92         testl   $0x80000000,%eax
  93         je      L_bugged
  94 
  95         testl   $0x80000000,SIGH(%esi)
  96         je      L_bugged
  97 #endif PARANOID
  98 
  99 /* The number to be shifted is in %eax:%ebx:%edx */
 100         cmpw    $32,%cx         /* shrd only works for 0..31 bits */
 101         jnc     L_more_than_31
 102 
 103 /* less than 32 bits */
 104         shrd    %cl,%ebx,%edx
 105         shrd    %cl,%eax,%ebx
 106         shr     %cl,%eax
 107         jmp     L_shift_done
 108 
 109 L_more_than_31:
 110         cmpw    $64,%cx
 111         jnc     L_more_than_63
 112 
 113         subb    $32,%cl
 114         jz      L_exactly_32
 115 
 116         shrd    %cl,%eax,%edx
 117         shr     %cl,%eax
 118         orl     %ebx,%ebx
 119         jz      L_more_31_no_low        /* none of the lowest bits is set */
 120 
 121         orl     $1,%edx                 /* record the fact in the extension */
 122 
 123 L_more_31_no_low:
 124         movl    %eax,%ebx
 125         xorl    %eax,%eax
 126         jmp     L_shift_done
 127 
 128 L_exactly_32:
 129         movl    %ebx,%edx
 130         movl    %eax,%ebx
 131         xorl    %eax,%eax
 132         jmp     L_shift_done
 133 
 134 L_more_than_63:
 135         cmpw    $65,%cx
 136         jnc     L_more_than_64
 137 
 138         movl    %eax,%edx
 139         orl     %ebx,%ebx
 140         jz      L_more_63_no_low
 141 
 142         orl     $1,%edx
 143         jmp     L_more_63_no_low
 144 
 145 L_more_than_64:
 146         movl    $1,%edx         /* The shifted nr always at least one '1' */
 147 
 148 L_more_63_no_low:
 149         xorl    %ebx,%ebx
 150         xorl    %eax,%eax
 151 
 152 L_shift_done:
 153         /* Now do the addition */
 154         addl    SIGL(%esi),%ebx
 155         adcl    SIGH(%esi),%eax
 156         jnc     L_round_the_result
 157 
 158         /* Overflow, adjust the result */
 159         rcrl    $1,%eax
 160         rcrl    $1,%ebx
 161         rcrl    $1,%edx
 162         jnc     L_no_bit_lost
 163 
 164         orl     $1,%edx
 165 
 166 L_no_bit_lost:
 167         incl    EXP(%edi)
 168 
 169 L_round_the_result:
 170         jmp     fpu_reg_round   /* Round the result */
 171 
 172 
 173 
 174 #ifdef PARANOID
 175 /* If we ever get here then we have problems! */
 176 L_bugged:
 177         pushl   EX_INTERNAL|0x201
 178         call    EXCEPTION
 179         pop     %ebx
 180         jmp     L_exit
 181 #endif PARANOID
 182 
 183 
 184 L_exit:
 185         popl    %ebx
 186         popl    %edi
 187         popl    %esi
 188         leave
 189         ret
/* */
root/drivers/FPU-emu/reg_u_add.S
