asm context issue? - Printable Version

asm context issue? - Printable Version

+- Forum (https://www.boriel.com/forum)
+-- Forum: Compilers and Computer Languages (https://www.boriel.com/forum/forumdisplay.php?fid=12)
+--- Forum: ZX Basic Compiler (https://www.boriel.com/forum/forumdisplay.php?fid=11)
+---- Forum: Help & Support (https://www.boriel.com/forum/forumdisplay.php?fid=16)
+---- Thread: asm context issue? (/showthread.php?tid=391)

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

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 - 10-25-2011

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 - 10-26-2011

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 - 10-26-2011

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: