83:OS:ROMPage0C - Revision history

CVSoft: /* Indirect ROM Calls, 4F0C to 51F2 */ whoops

2015-12-13T11:20:53Z

‎Indirect ROM Calls, 4F0C to 51F2: whoops

CVSoft: Ugly spacing is ugly

2015-12-13T11:17:38Z

Ugly spacing is ugly

CVSoft: Lots more documentation, mostly about indirect ROM calls.

2015-12-13T11:16:29Z

Lots more documentation, mostly about indirect ROM calls.

Guillaumeh at 20:47, 26 April 2005

2005-04-26T20:47:30Z

New page

[[Category:83:OS Information|ROM Page 0C]]

This ROM page is loaded as soon as an ASM program is launched.

==Structure==

===4000===
Here is the ROM Call jumptable, which looks like this :

<nowiki>
call 0033
ret
call 010F
ret
call 011B
ret
call 111F
ret
...</nowiki>

... seldom having some jumps instead of calls.

At 4F0C, the ROM Calls start to look like this :

<nowiki>
pusf af
ld a,XX
ld (80C8),a
pop af
jr 5188
</nowiki>

===52E9===
This part only has FF FF FF FF FF ... until the end (7FFF).

@@ Line 24: / Line 24: @@
 At 4F0C, the ROM Calls start to look like this :
-<nowiki>
+ <nowiki>
 	push	af
 	ld	a,XX
@@ Line 34: / Line 34: @@
 Calling a routine that uses the above format in the jump table loads a table index in ASM_IND_CALL (80C8), then goes to one of two handlers. The jr address calls either PARSER_EXEC (for addresses between 4F0C and 50A9) or GRAPH_EXEC (between 510A and 51E6). PARSER_EXEC goes to page $09 and GRAPH_EXEC goes to page $04. After calling a routine in one of those two ranges, the OS calls a handler on the corresponding page that adds 2*(80C8) (memory addresses are two bytes) to the start address of the address table, puts that value on the stack, and rets to that address.
 There is a region between 50B2 and 5109 that contain normal calls, like those around 4000. GRAPH_EXEC, PARSER_EXEC, and IO_EXEC are also normal calls.
 ===51F3 to 52E8===

← Older revision		Revision as of 11:17, 13 December 2015
Line 1:		Line 1:
	[[Category:83:OS Information\|ROM Page 0C]]		[[Category:83:OS Information\|ROM Page 0C]]
−
	This ROM page is loaded as soon as an ASM program is launched.		This ROM page is loaded as soon as an ASM program is launched.

@@ Line 5: / Line 5: @@
 ==Structure==
-===4000===
+===Direct Calls, 4000 to 4F0B===
 Here is the ROM Call jumptable, which looks like this :
@@ Line 20: / Line 20: @@
 ... seldom having some jumps instead of calls.
 At 4F0C, the ROM Calls start to look like this :
- <nowiki>
+<nowiki>
-	pusf	af
+	push	af
 	ld	a,XX
 	ld	(80C8),a
@@ Line 31: / Line 33: @@
 </nowiki>
-===52E9===
+===52E9 to 7FFF===
 This part only has FF FF FF FF FF ... until the end (7FFF).