Intravision/reactos
1
0
Fork 0
mirror of https://github.com/reactos/reactos.git synced 2025-05-29 05:58:13 +00:00
Code Issues Projects Releases Packages Wiki Activity

[SOFTX86]

Browse source 
Fix carry/overflow flag computation for ADD instructions.


svn path=/branches/ntvdm/; revision=59725
This commit is contained in:
Aleksandar Andrejevic 2013-08-13 17:06:15 +00:00
parent e387f7f1cd
commit a88f650367
1 changed files with 31 additions and 21 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

52
lib/3rdparty/softx86/softx86/add.c vendored
View file

@ -35,13 +35,16 @@ sx86_ubyte op_add8(softx86_ctx* ctx,sx86_ubyte src,sx86_ubyte val)
/* peform the addition */ /* peform the addition */
ret = src + val; ret = src + val;
/* if carry/overflow */ /* if carry */
if (ret < src) if ((ret < src) || (ret < val)) ctx->state->reg_flags.val |= SX86_CPUFLAG_CARRY;
ctx->state->reg_flags.val |= else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
else /* if overflow */
ctx->state->reg_flags.val &= if (((src & 0x80) == (val & 0x80)) && ((src & 0x80) != (ret & 0x80)))
~(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW); {
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 result treated as signed value is negative */
if (ret & 0x80) ctx->state->reg_flags.val |= SX86_CPUFLAG_SIGN; if (ret & 0x80) ctx->state->reg_flags.val |= SX86_CPUFLAG_SIGN;
@ -79,13 +82,16 @@ sx86_uword op_add16(softx86_ctx* ctx,sx86_uword src,sx86_uword val)
/* peform the addition */ /* peform the addition */
ret = src + val; ret = src + val;
/* if carry/overflow */ /* if carry */
if (ret < src) if ((ret < src) || (ret < val)) ctx->state->reg_flags.val |= SX86_CPUFLAG_CARRY;
ctx->state->reg_flags.val |= else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
else /* if overflow */
ctx->state->reg_flags.val &= if (((src & 0x8000) == (val & 0x8000)) && ((src & 0x8000) != (ret & 0x8000)))
~(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW); {
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 result treated as signed value is negative */
if (ret & 0x8000) if (ret & 0x8000)
@ -125,13 +131,17 @@ sx86_udword op_add32(softx86_ctx* ctx,sx86_udword src,sx86_udword val)
/* peform the addition */ /* peform the addition */
ret = src + val; ret = src + val;
/* if carry/overflow */ /* if carry */
if (ret < src) if ((ret < src) || (ret < val)) ctx->state->reg_flags.val |= SX86_CPUFLAG_CARRY;
ctx->state->reg_flags.val |= else ctx->state->reg_flags.val &= ~SX86_CPUFLAG_CARRY;
(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW);
else /* if overflow */
ctx->state->reg_flags.val &= if (((src & 0x80000000) == (val & 0x80000000))
~(SX86_CPUFLAG_CARRY | SX86_CPUFLAG_OVERFLOW); && ((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 result treated as signed value is negative */
if (ret & 0x80000000) if (ret & 0x80000000)