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135 lines
3.9 KiB
135 lines
3.9 KiB
/*---------------------------------------------------------------------------+
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| polynomial_Xsig.S |
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| Fixed point arithmetic polynomial evaluation. |
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| Copyright (C) 1992,1993,1994,1995 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@jacobi.maths.monash.edu.au |
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| Call from C as: |
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| void polynomial_Xsig(Xsig *accum, unsigned long long x, |
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| unsigned long long terms[], int n) |
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| Computes: |
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| terms[0] + (terms[1] + (terms[2] + ... + (terms[n-1]*x)*x)*x)*x) ... )*x |
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| and adds the result to the 12 byte Xsig. |
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| The terms[] are each 8 bytes, but all computation is performed to 12 byte |
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| precision. |
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| This function must be used carefully: most overflow of intermediate |
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| results is controlled, but overflow of the result is not. |
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+---------------------------------------------------------------------------*/
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.file "polynomial_Xsig.S"
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#include "fpu_emu.h"
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#define TERM_SIZE $8
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#define SUM_MS -20(%ebp) /* sum ms long */
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#define SUM_MIDDLE -24(%ebp) /* sum middle long */
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#define SUM_LS -28(%ebp) /* sum ls long */
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#define ACCUM_MS -4(%ebp) /* accum ms long */
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#define ACCUM_MIDDLE -8(%ebp) /* accum middle long */
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#define ACCUM_LS -12(%ebp) /* accum ls long */
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#define OVERFLOWED -16(%ebp) /* addition overflow flag */
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.text
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ENTRY(polynomial_Xsig)
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pushl %ebp
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movl %esp,%ebp
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subl $32,%esp
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pushl %esi
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pushl %edi
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pushl %ebx
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movl PARAM2,%esi /* x */
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movl PARAM3,%edi /* terms */
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movl TERM_SIZE,%eax
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mull PARAM4 /* n */
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addl %eax,%edi
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movl 4(%edi),%edx /* terms[n] */
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movl %edx,SUM_MS
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movl (%edi),%edx /* terms[n] */
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movl %edx,SUM_MIDDLE
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xor %eax,%eax
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movl %eax,SUM_LS
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movb %al,OVERFLOWED
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subl TERM_SIZE,%edi
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decl PARAM4
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js L_accum_done
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L_accum_loop:
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xor %eax,%eax
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movl %eax,ACCUM_MS
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movl %eax,ACCUM_MIDDLE
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movl SUM_MIDDLE,%eax
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mull (%esi) /* x ls long */
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movl %edx,ACCUM_LS
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movl SUM_MIDDLE,%eax
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mull 4(%esi) /* x ms long */
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addl %eax,ACCUM_LS
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adcl %edx,ACCUM_MIDDLE
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adcl $0,ACCUM_MS
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movl SUM_MS,%eax
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mull (%esi) /* x ls long */
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addl %eax,ACCUM_LS
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adcl %edx,ACCUM_MIDDLE
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adcl $0,ACCUM_MS
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movl SUM_MS,%eax
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mull 4(%esi) /* x ms long */
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addl %eax,ACCUM_MIDDLE
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adcl %edx,ACCUM_MS
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testb $0xff,OVERFLOWED
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jz L_no_overflow
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movl (%esi),%eax
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addl %eax,ACCUM_MIDDLE
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movl 4(%esi),%eax
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adcl %eax,ACCUM_MS /* This could overflow too */
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L_no_overflow:
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/*
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* Now put the sum of next term and the accumulator
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* into the sum register
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*/
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movl ACCUM_LS,%eax
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addl (%edi),%eax /* term ls long */
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movl %eax,SUM_LS
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movl ACCUM_MIDDLE,%eax
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adcl (%edi),%eax /* term ls long */
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movl %eax,SUM_MIDDLE
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movl ACCUM_MS,%eax
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adcl 4(%edi),%eax /* term ms long */
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movl %eax,SUM_MS
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sbbb %al,%al
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movb %al,OVERFLOWED /* Used in the next iteration */
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subl TERM_SIZE,%edi
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decl PARAM4
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jns L_accum_loop
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L_accum_done:
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movl PARAM1,%edi /* accum */
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movl SUM_LS,%eax
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addl %eax,(%edi)
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movl SUM_MIDDLE,%eax
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adcl %eax,4(%edi)
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movl SUM_MS,%eax
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adcl %eax,8(%edi)
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popl %ebx
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popl %edi
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popl %esi
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leave
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ret
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