izaya/collapseos
1
0
Fork 0
mirror of https://github.com/hsoft/collapseos.git synced 2024-11-24 04:58:06 +11:00
Code Issues Releases Wiki Activity

core: preserve A in cpHLDE

Browse Source
This commit is contained in:
Virgil Dupras 2019-07-23 22:59:10 -04:00
parent 1c6a7caeae
commit 985d56ca5a
1 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
kernel/core.asm
View File

@ -84,13 +84,22 @@ subHL:
; Compare HL with DE and sets Z and C in the same way as a regular cp X where ; Compare HL with DE and sets Z and C in the same way as a regular cp X where
; HL is A and DE is X. ; HL is A and DE is X.
; A is preserved through some register hocus pocus: having cpHLDE destroying
; A bit me too many times.
cpHLDE: cpHLDE:
push bc
ld b, a ; preserve A
ld a, h ld a, h
cp d cp d
ret nz ; if not equal, flags are correct jr nz, .end ; if not equal, flags are correct
ld a, l ld a, l
cp e cp e
ret ; flags are correct ; flags are correct
.end:
; restore A but don't touch flags
ld a, b
pop bc
ret
; Write the contents of HL in (DE) ; Write the contents of HL in (DE)
writeHLinDE: writeHLinDE: