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| /* SPDX-License-Identifier: GPL-2.0 */
| .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
| SYM_FUNC_START(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 */
|
| SYM_FUNC_END(FPU_u_mul)
|
|
