| .file "reg_u_mul.S" |
| /*---------------------------------------------------------------------------+ |
| | reg_u_mul.S | |
| | | |
| | Core multiplication routine | |
| | | |
| | Copyright (C) 1992,1993,1995,1997 | |
| | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | |
| | E-mail billm@suburbia.net | |
| | | |
| | | |
| +---------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------+ |
| | Basic multiplication routine. | |
| | Does not check the resulting exponent for overflow/underflow | |
| | | |
| | FPU_u_mul(FPU_REG *a, FPU_REG *b, FPU_REG *c, unsigned int cw); | |
| | | |
| | Internal working is at approx 128 bits. | |
| | Result is rounded to nearest 53 or 64 bits, using "nearest or even". | |
| +---------------------------------------------------------------------------*/ |
| |
| #include "exception.h" |
| #include "fpu_emu.h" |
| #include "control_w.h" |
| |
| |
| |
| #ifndef NON_REENTRANT_FPU |
| /* Local storage on the stack: */ |
| #define FPU_accum_0 -4(%ebp) /* ms word */ |
| #define FPU_accum_1 -8(%ebp) |
| |
| #else |
| /* Local storage in a static area: */ |
| .data |
| .align 4,0 |
| FPU_accum_0: |
| .long 0 |
| FPU_accum_1: |
| .long 0 |
| #endif /* NON_REENTRANT_FPU */ |
| |
| |
| .text |
| ENTRY(FPU_u_mul) |
| pushl %ebp |
| movl %esp,%ebp |
| #ifndef NON_REENTRANT_FPU |
| subl $8,%esp |
| #endif /* NON_REENTRANT_FPU */ |
| |
| pushl %esi |
| pushl %edi |
| pushl %ebx |
| |
| movl PARAM1,%esi |
| movl PARAM2,%edi |
| |
| #ifdef PARANOID |
| testl $0x80000000,SIGH(%esi) |
| jz L_bugged |
| testl $0x80000000,SIGH(%edi) |
| jz L_bugged |
| #endif /* PARANOID */ |
| |
| xorl %ecx,%ecx |
| xorl %ebx,%ebx |
| |
| movl SIGL(%esi),%eax |
| mull SIGL(%edi) |
| movl %eax,FPU_accum_0 |
| movl %edx,FPU_accum_1 |
| |
| movl SIGL(%esi),%eax |
| mull SIGH(%edi) |
| addl %eax,FPU_accum_1 |
| adcl %edx,%ebx |
| /* adcl $0,%ecx // overflow here is not possible */ |
| |
| movl SIGH(%esi),%eax |
| mull SIGL(%edi) |
| addl %eax,FPU_accum_1 |
| adcl %edx,%ebx |
| adcl $0,%ecx |
| |
| movl SIGH(%esi),%eax |
| mull SIGH(%edi) |
| addl %eax,%ebx |
| adcl %edx,%ecx |
| |
| /* Get the sum of the exponents. */ |
| movl PARAM6,%eax |
| subl EXP_BIAS-1,%eax |
| |
| /* Two denormals can cause an exponent underflow */ |
| cmpl EXP_WAY_UNDER,%eax |
| jg Exp_not_underflow |
| |
| /* Set to a really low value allow correct handling */ |
| movl EXP_WAY_UNDER,%eax |
| |
| Exp_not_underflow: |
| |
| /* Have now finished with the sources */ |
| movl PARAM3,%edi /* Point to the destination */ |
| movw %ax,EXP(%edi) |
| |
| /* Now make sure that the result is normalized */ |
| testl $0x80000000,%ecx |
| jnz LResult_Normalised |
| |
| /* Normalize by shifting left one bit */ |
| shll $1,FPU_accum_0 |
| rcll $1,FPU_accum_1 |
| rcll $1,%ebx |
| rcll $1,%ecx |
| decw EXP(%edi) |
| |
| LResult_Normalised: |
| movl FPU_accum_0,%eax |
| movl FPU_accum_1,%edx |
| orl %eax,%eax |
| jz L_extent_zero |
| |
| orl $1,%edx |
| |
| L_extent_zero: |
| movl %ecx,%eax |
| jmp fpu_reg_round |
| |
| |
| #ifdef PARANOID |
| L_bugged: |
| pushl EX_INTERNAL|0x205 |
| call EXCEPTION |
| pop %ebx |
| jmp L_exit |
| |
| L_exit: |
| popl %ebx |
| popl %edi |
| popl %esi |
| leave |
| ret |
| #endif /* PARANOID */ |
| |
