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150 lines
3.6 KiB
150 lines
3.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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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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SYM_FUNC_START(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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SYM_FUNC_END(FPU_u_mul)
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