Difference between revisions of "84PCE:RAM:D01508"

Revision as of 07:28, 26 May 2016

Unofficial Name: tempSP

Memory Address: D0053Fh

Length: 3 bytes

When the OS is checking the stack depth, it uses this region of memory to load hl with sp. For instance:

ld (tempSP),sp
ld hl,(tempSP)

It can generally be used as a temporary data location, although it may be written to at some points.

However, it is simply beyond me why they didn't simply do this, to save a ton of bytes and speed.

or a,a
sbc hl,hl
add hl,sp

@@ Line 1: / Line 1: @@
-[[Category:84PCE:RAM:By Address|D01508 - lastEntryStkPtr]] [[Category:84PCE:RAM:By Name|lastEntryStkPtr]]
+[[Category:84PCE:RAM:By Address|D0053F - tempSP]] [[Category:84PCE:RAM:By Name|tempSP]]
 == Synopsis ==
-'''Unofficial Name:''' lastEntryStkPtr
+'''Unofficial Name:''' tempSP
-'''Memory Address:''' D01508h
+'''Memory Address:''' D0053Fh
 '''Length:''' 3 bytes
-This is a pointer to the next available byte in the user entry stack.
+When the OS is checking the stack depth, it uses this region of memory to load hl with sp. For instance:
+ ld (tempSP),sp
+ ld hl,(tempSP)
+It can generally be used as a temporary data location, although it may be written to at some points.
+==Why this is silly==
+However, it is simply beyond me why they didn't simply do this, to save a ton of bytes and speed.
+ or a,a
+ sbc hl,hl
+ add hl,sp