ASM problem

[Georg Potthast]

I try to code this statement:

asm shl ah,6

This results in an assembler syntax error. What is the correct syntax?

Georg

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[Bob Zale]

Hi Georg!

SHL ah, 6 is not a valid 8086 opcode. It was introduced on a later model CPU. Since PB/DOS supports the 8086/8088, the ASM statement in PB/DOS only assembles 8086/8088 opcodes.

You could change it to:

MOV cl, 6
SHL ah, cl

---or---

SHL ah, 1
SHL ah, 1
SHL ah, 1
SHL ah, 1
SHL ah, 1
SHL ah, 1

---or---

ASM db &H0C0
ASM db &H0E4
ASM db &H006

(which is the machine code translation)

Best regards,

Bob Zale
PowerBASIC Inc.


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[Georg Potthast]

Hi Bob,

thank you for your detailed answer. As I found, the last alternative can be used to implement pusha/popa as well:

asm db &H60 ;pusha
asm db &H61 ;popa

Best regards

Georg

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