PUSHAD/POPAD available?

[Clay Clear]

Are the verbs "PUSHAD" and "POPAD" available for use in PB/DOS 3.5's
inline assembler? If they are, can you please provide the syntax
for their use? I tried: ! PUSHAD, and got an assembler
error message when trying to compile it.

Thanks in advance!

Cordially,


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Clay C. Clear
mailto:[email protected][email protected]</A>
Clay Clear's Software (Frames Only)

[Tom Hanlin]

According the help for the ASM statement, "PowerBASIC supports assembly of all 8086/8088 opcodes directly..."

PUSHAD and POPAD require an 80386 or later.

You can code them directly as machine code, though. PUSHAD is the same as:

! db &H66
! db &H60

For POPAD, use:

! db &H66
! db &H61

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Tom Hanlin
PowerBASIC Staff

[Clay Clear]

Thanks, Tom, not just for your reply, but also for the
workaround.

Regards,


------------------
Clay C. Clear
mailto:[email protected][email protected]</A>
Clay Clear's Software (Frames Only)

[Tom Hanlin]

De nada. Note that the "&H60" and "&H61" are really the opcodes for
PUSHA and POPA, respectively. What the leading "&H66" says, in this
context, is "consider the next code as a 32-bit instruction, not a 16-bit
instruction". You can use the leading "&H66" trick in many similar cases
to boost a 16-bit instruction to a 32-bit instruction. For example:

! db &H66
! xor ax, ax

What this really translates to is, "xor eax, eax".

We can't use this technique to boost PUSHA to PUSHAD or POPA to POPAD
because, unfortunately, PUSHA and POPA aren't 8088-level instructions
either. They require at least an 80186. So, we have to use the full
machine-language numeric encoding, instead of just a "&H66" prefix
to the assembly-language mnemonics.

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Tom Hanlin
PowerBASIC Staff

[Clay Clear]

Cool! Thanks! As I venture further into the world of PC
assembly programming (I'm LOADED with machine language assembly
stuff on the Commodore-64...pretty archane knowledge <chuckle> )
, such knowledge will come in VERY handy.

Thanks.

Regards,


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Clay C. Clear
mailto:[email protected][email protected]</A>
Clay Clear's Software (Frames Only)