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