74 lines
1.5 KiB
C
74 lines
1.5 KiB
C
/*
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* linux/kernel/math/mul.c
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*
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* (C) 1991 Linus Torvalds
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*/
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/*
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* temporary real multiplication routine.
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*/
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#include <linux/math_emu.h>
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static void shift(int * c)
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{
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__asm__("movl (%0),%%eax ; addl %%eax,(%0)\n\t"
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"movl 4(%0),%%eax ; adcl %%eax,4(%0)\n\t"
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"movl 8(%0),%%eax ; adcl %%eax,8(%0)\n\t"
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"movl 12(%0),%%eax ; adcl %%eax,12(%0)"
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::"r" ((long) c):"ax");
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}
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static void mul64(const temp_real * a, const temp_real * b, int * c)
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{
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__asm__("movl (%0),%%eax\n\t"
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"mull (%1)\n\t"
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"movl %%eax,(%2)\n\t"
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"movl %%edx,4(%2)\n\t"
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"movl 4(%0),%%eax\n\t"
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"mull 4(%1)\n\t"
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"movl %%eax,8(%2)\n\t"
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"movl %%edx,12(%2)\n\t"
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"movl (%0),%%eax\n\t"
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"mull 4(%1)\n\t"
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"addl %%eax,4(%2)\n\t"
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"adcl %%edx,8(%2)\n\t"
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"adcl $0,12(%2)\n\t"
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"movl 4(%0),%%eax\n\t"
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"mull (%1)\n\t"
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"addl %%eax,4(%2)\n\t"
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"adcl %%edx,8(%2)\n\t"
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"adcl $0,12(%2)"
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::"b" ((long) a),"c" ((long) b),"D" ((long) c)
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:"ax","dx");
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}
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void fmul(const temp_real * src1, const temp_real * src2, temp_real * result)
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{
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int i,sign;
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int tmp[4] = {0,0,0,0};
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sign = (src1->exponent ^ src2->exponent) & 0x8000;
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i = (src1->exponent & 0x7fff) + (src2->exponent & 0x7fff) - 16383 + 1;
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if (i<0) {
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result->exponent = sign;
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result->a = result->b = 0;
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return;
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}
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if (i>0x7fff) {
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set_OE();
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return;
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}
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mul64(src1,src2,tmp);
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if (tmp[0] || tmp[1] || tmp[2] || tmp[3])
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while (i && tmp[3] >= 0) {
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i--;
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shift(tmp);
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}
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else
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i = 0;
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result->exponent = i | sign;
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result->a = tmp[2];
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result->b = tmp[3];
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}
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