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