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fixed problems in BCD instructions

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This commit is contained in:
Stanislav Shwartsman 2004-03-10 20:14:56 +00:00
parent 87853190b5
commit 58a7652aea
1 changed files with 44 additions and 26 deletions
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70
bochs/cpu/bcd.cc
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@ -1,5 +1,5 @@
/////////////////////////////////////////////////////////////////////////
// $Id: bcd.cc,v 1.8 2004-03-09 20:45:17 sshwarts Exp $
// $Id: bcd.cc,v 1.9 2004-03-10 20:14:56 sshwarts Exp $
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2002 MandrakeSoft S.A.
@ -38,12 +38,12 @@
void
BX_CPU_C::DAS(bxInstruction_c *)
{
/* the algorithm for DAS is fashioned after the pseudo code in the
/* The algorithm for DAS is fashioned after the pseudo code in the
* Pentium Processor Family Developer's Manual, volume 3. It seems
* to have changed from earlier processor's manuals. I'm not sure
* if this is a correction in the algorithm printed, or Intel has
* changed the handling of instruction. It might not even be
* correct yet...
* changed the handling of instruction. Validated against Intel
* Pentium family hardware.
*/
Bit8u tmpAL = AL;
@ -51,16 +51,16 @@ BX_CPU_C::DAS(bxInstruction_c *)
/* DAS effect the following flags: A,C,S,Z,P */
if (((AL & 0x0F) > 0x09) || get_AF())
if (((tmpAL & 0x0F) > 0x09) || get_AF())
{
tmpAL = AL - 0x06;
if ((AL < 0x06) || get_CF()) tmpCF = 1;
tmpCF = (AL < 0x06) || get_CF();
AL = AL - 0x06;
set_AF(1);
}
else
set_AF(0);
if ((AL > 0x99) || get_CF())
if ((tmpAL > 0x99) || get_CF())
{
AL = AL - 0x60;
tmpCF = 1;
@ -68,22 +68,40 @@ BX_CPU_C::DAS(bxInstruction_c *)
else
tmpCF = 0;
AL = tmpAL;
set_CF(tmpCF);
set_SF(tmpAL >> 7);
set_ZF(tmpAL==0);
set_PF_base(tmpAL);
set_SF(AL >> 7);
set_ZF(AL==0);
set_PF_base(AL);
}
void
BX_CPU_C::AAA(bxInstruction_c *)
{
/*
* Note: This istruction incorrectly documented in Intel's materials.
* The right description is:
*
* IF (((AL and 0FH) > 9) or (AF==1)
* THEN {
* IF CPU<286 THEN { AL <- AL+6 }
* ELSE { AX <- AX+6 }
* AH <- AH+1
* CF <- 1
* AF <- 1
* } ELSE {
* CF <- 0
* AF <- 0
* }
* AL <- AL and 0Fh
*/
/* Validated against Intel Pentium family hardware. */
/* AAA affects the following flags: A,C */
if ( ((AL & 0x0f) > 9) || get_AF() )
{
AL = AL + 6;
AX = AX + 6;
AH = AH + 1;
set_AF(1);
set_CF(1);
@ -103,7 +121,7 @@ BX_CPU_C::AAS(bxInstruction_c *)
if ( ((AL & 0x0F) > 0x09) || get_AF() )
{
AL = AL - 6;
AL = AL - 6; /* never borrow */
AH = AH - 1;
set_AF(1);
set_CF(1);
@ -168,31 +186,31 @@ BX_CPU_C::AAD(bxInstruction_c *i)
BX_CPU_C::DAA(bxInstruction_c *)
{
Bit8u tmpAL = AL;
int tmpCF = 0;
int tmpCF = 0;
/* Validated against Intel Pentium family hardware. */
// DAA affects the following flags: S,Z,A,P,C
if (((AL & 0x0F) > 0x09) || get_AF())
if (((tmpAL & 0x0F) > 0x09) || get_AF())
{
tmpAL = AL + 0x06;
if (get_CF() || (tmpAL < AL)) tmpCF = 1;
tmpCF = ((AL > 0xF9) || get_CF());
AL = AL + 0x06;
set_AF(1);
}
else
set_AF(0);
if ((AL > 0x99) || get_CF())
if ((tmpAL > 0x99) || get_CF())
{
tmpAL = AL + 0x60;
AL = AL + 0x60;
tmpCF = 1;
}
else
tmpCF = 0;
AL = tmpAL;
set_CF(tmpCF);
set_SF(tmpAL >> 7);
set_ZF(tmpAL==0);
set_PF_base(tmpAL);
set_SF(AL >> 7);
set_ZF(AL==0);
set_PF_base(AL);
}