kernel/math/mul.c

/* */
This source file includes following definitions.
shift
mul64
fmul
   1 /*
   2  * linux/kernel/math/mul.c
   3  *
   4  * Copyright (C) 1991, 1992 Linus Torvalds
   5  */
   6 
   7 /*
   8  * temporary real multiplication routine.
   9  */
  10 
  11 #include <linux/math_emu.h>
  12 
  13 static void shift(int * c)
     /*  */
  14 {
  15         __asm__("movl (%0),%%eax ; addl %%eax,(%0)\n\t"
  16                 "movl 4(%0),%%eax ; adcl %%eax,4(%0)\n\t"
  17                 "movl 8(%0),%%eax ; adcl %%eax,8(%0)\n\t"
  18                 "movl 12(%0),%%eax ; adcl %%eax,12(%0)"
  19                 ::"r" ((long) c):"ax");
  20 }
  21 
  22 static void mul64(const temp_real * a, const temp_real * b, int * c)
     /*  */
  23 {
  24         __asm__("movl (%0),%%eax\n\t"
  25                 "mull (%1)\n\t"
  26                 "movl %%eax,(%2)\n\t"
  27                 "movl %%edx,4(%2)\n\t"
  28                 "movl 4(%0),%%eax\n\t"
  29                 "mull 4(%1)\n\t"
  30                 "movl %%eax,8(%2)\n\t"
  31                 "movl %%edx,12(%2)\n\t"
  32                 "movl (%0),%%eax\n\t"
  33                 "mull 4(%1)\n\t"
  34                 "addl %%eax,4(%2)\n\t"
  35                 "adcl %%edx,8(%2)\n\t"
  36                 "adcl $0,12(%2)\n\t"
  37                 "movl 4(%0),%%eax\n\t"
  38                 "mull (%1)\n\t"
  39                 "addl %%eax,4(%2)\n\t"
  40                 "adcl %%edx,8(%2)\n\t"
  41                 "adcl $0,12(%2)"
  42                 ::"S" ((long) a),"c" ((long) b),"D" ((long) c)
  43                 :"ax","dx");
  44 }
  45 
  46 void fmul(const temp_real * src1, const temp_real * src2, temp_real * result)
     /*  */
  47 {
  48         int i,sign;
  49         int tmp[4] = {0,0,0,0};
  50 
  51         sign = (src1->exponent ^ src2->exponent) & 0x8000;
  52         i = (src1->exponent & 0x7fff) + (src2->exponent & 0x7fff) - 16383 + 1;
  53         if (i<0) {
  54                 result->exponent = sign;
  55                 result->a = result->b = 0;
  56                 return;
  57         }
  58         if (i>0x7fff) {
  59                 set_OE();
  60                 return;
  61         }
  62         mul64(src1,src2,tmp);
  63         if (tmp[0] || tmp[1] || tmp[2] || tmp[3])
  64                 while (i && tmp[3] >= 0) {
  65                         i--;
  66                         shift(tmp);
  67                 }
  68         else
  69                 i = 0;
  70         result->exponent = i | sign;
  71         result->a = tmp[2];
  72         result->b = tmp[3];
  73 }
/* */
root/kernel/math/mul.c

DEFINITIONS
