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[SOFTX86]

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Fix carry/overflow condition for the SUB instruction.


svn path=/branches/ntvdm/; revision=59490
This commit is contained in:
Aleksandar Andrejevic 2013-07-15 02:34:45 +00:00
parent 40d639e7ff
commit f82876686a
1 changed files with 25 additions and 15 deletions
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40
lib/3rdparty/softx86/softx86/add.c vendored
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@ -342,13 +342,16 @@ sx86_ubyte op_sub8(softx86_ctx* ctx,sx86_ubyte src,sx86_ubyte val)
/* peform the addition */
ret = src - val;
/* if carry/overflow */
if (ret > src)
ctx->state->reg_flags.val |=
(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
else
ctx->state->reg_flags.val &=
~(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
/* if carry */
if (val > src) ctx->state->reg_flags.val |= SX86_CPUFLAG_CARRY;
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
/* if overflow */
if (((src & 0x80) != (val & 0x80)) && ((src & 0x80) != (ret & 0x80)))
{
ctx->state->reg_flags.val |= SX86_CPUFLAG_OVERFLOW;
}
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_OVERFLOW;
/* if result treated as signed value is negative */
if (ret & 0x80) ctx->state->reg_flags.val |= SX86_CPUFLAG_SIGN;
@ -391,7 +394,10 @@ sx86_uword op_sub16(softx86_ctx* ctx,sx86_uword src,sx86_uword val)
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
/* if overflow */
if ((ret & 0x8000) != (src & 0x8000)) ctx->state->reg_flags.val |= SX86_CPUFLAG_OVERFLOW;
if (((src & 0x8000) != (val & 0x8000)) && ((src & 0x8000) != (ret & 0x8000)))
{
ctx->state->reg_flags.val |= SX86_CPUFLAG_OVERFLOW;
}
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_OVERFLOW;
/* if result treated as signed value is negative */
@ -430,13 +436,17 @@ sx86_udword op_sub32(softx86_ctx* ctx,sx86_udword src,sx86_udword val)
/* peform the addition */
ret = src - val;
/* if carry/overflow */
if (ret > src)
ctx->state->reg_flags.val |=
(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
else
ctx->state->reg_flags.val &=
~(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
/* if carry */
if (val > src) ctx->state->reg_flags.val |= SX86_CPUFLAG_CARRY;
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
/* if overflow */
if (((src & 0x80000000) != (val & 0x80000000))
&& ((src & 0x80000000) != (ret & 0x80000000)))
{
ctx->state->reg_flags.val |= SX86_CPUFLAG_OVERFLOW;
}
else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_OVERFLOW;
/* if result treated as signed value is negative */
if (ret & 0x80000000) ctx->state->reg_flags.val |= SX86_CPUFLAG_SIGN;