asm context issue? - Printable Version

asm context issue? - Printable Version

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asm context issue? - britlion - 2011-10-25

Code:
asm

sub a,3

end asm

I think this is expecting sub to be the basic context subroutine, not the asm subtract command, so fails to compile?

zxb 1.2.8-s758

Re: asm context issue? - boriel - 2011-10-25

According to the ZX Spectrum manual, the Z80 syntax instruction is sub N not sub a, N for 8 bits.
So:

Code:
asm

sub 3

end asm

should work ok.
Try this and tell me :?:

Re: asm context issue? - britlion - 2011-10-26

Ugh.

Looks like my reference may be incorrect:

Code:
SUB A,imm8

Operation Subtracts the immediate value from A. 

Op Code 11010110 : [imm8] 

Flags S Z H C are affected as defined

P/V detects overflow

N is set 

T States 7

You're right. It looks like Zilog officially use SUB N - which is inconsistent with all their other instructions! How bizarre!

Re: asm context issue? - boriel - 2011-10-26

I used the speccy user manual to get the asm mnemonics! :mrgreen:
Anyway, I will try to make de ASM to allow SUB A, N also. :roll: