84PCE:Syscalls:021D80 - Revision history

MateoConLechuga: /* Synopsis */

2015-09-04T20:05:13Z

‎Synopsis

MateoConLechuga at 19:59, 4 September 2015

2015-09-04T19:59:52Z

MateoConLechuga at 19:56, 4 September 2015

2015-09-04T19:56:40Z

MateoConLechuga at 19:56, 4 September 2015

2015-09-04T19:56:12Z

MateoConLechuga at 18:29, 4 September 2015

2015-09-04T18:29:22Z

MateoConLechuga: /* Synopsis */

2015-09-01T21:01:48Z

‎Synopsis

MateoConLechuga at 01:43, 5 May 2015

2015-05-05T01:43:19Z

MateoConLechuga: Created page with "SignExtendHL_broken 021D80 - SignExtendHL_broken == Synopsis == '''Hypothesized Official Name:''' Si..."

2015-05-05T01:42:24Z

Created page with "SignExtendHL_broken 021D80 - SignExtendHL_broken == Synopsis == '''Hypothesized Official Name:''' Si..."

New page

[[Category:84PCE:Syscalls:By Name|SignExtendHL_broken]]
[[Category:84PCE:Syscalls:By Address|021D80 - SignExtendHL_broken]]
== Synopsis ==
'''Hypothesized Official Name:''' SignExtendHL_broken

'''Syscall Address:''' 021D80h

This is supposed to extend the signed 16-bit HL value to be 24-bit signed.

However, due to what looks like a copy-paste error by TI, this routine is pretty much useless.

It looks like they tried to use code from SignExtendBC, and forgot to change a byte.

Here is what this routine calls, if you can find a particular use for it, go for it.

<nowiki>SignExtendDE_broken:
push af
xor a
ld (0D02AD7h), hl
bit 7, b ; This should be h, not b
jr z, _+
dec a
_+:
ld (0D02AD9h), a
ld de, (0D02AD7h)
pop af
ret </nowiki>

@@ Line 6: / Line 6: @@
 '''Syscall Address:''' 021D80h
-This was originally a broken call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL. It is known to work in OS 5.1.0.0110.
+This was originally a broken call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call.
 === Inputs ===

@@ Line 6: / Line 6: @@
 '''Syscall Address:''' 021D80h
-This was originally a broken call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.
+This was originally a broken call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL. It is known to work in OS 5.1.0.0110.
 === Inputs ===

@@ Line 6: / Line 6: @@
 '''Syscall Address:''' 021D80h
-This was originally a buggy call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.
+This was originally a broken call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.
 === Inputs ===

← Older revision		Revision as of 19:56, 4 September 2015
Line 7:		Line 7:

	This was originally a buggy call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.		This was originally a buggy call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.
		+
		+	=== Inputs ===
		+	HL - 16-bit signed value
		+
		+	=== Outputs ===
		+	HL - 24-bit signed value
		+
		+	=== Destroys ===
		+	* HLU

@@ Line 1: / Line 1: @@
-[[Category:84PCE:Syscalls:By Name|SignExtendHL_broken]]
+[[Category:84PCE:Syscalls:By Name|SignExtendHL]]
-[[Category:84PCE:Syscalls:By Address|021D80 - SignExtendHL_broken]]
+[[Category:84PCE:Syscalls:By Address|021D80 - SignExtendHL]]
 == Synopsis ==
-'''Hypothesized Official Name:''' SignExtendHL_broken
+'''Hypothesized Official Name:''' SignExtendHL
 '''Syscall Address:''' 021D80h
-This is supposed to extend the signed 16-bit HL value to be 24-bit signed.
+This was originally a buggy call, and still is in OS 5.0.0.0089 (and others, perchance?) But after sending in information, TI did an amazing job and fixed this call. It basically performs a sign extension on a 16bit HL to 24bit HL.
-−
-However, due to what looks like a copy-paste error by TI, this routine is pretty much useless.
-−
-It looks like they tried to use code from SignExtendBC, and forgot to change a byte.
-−
-Here is what this routine calls, if you can find a particular use for it, go for it.
-−
- <nowiki>SignExtendHL_broken:
- push af
-  xor a
-  ld (0D02AD7h), hl
-  bit 7, b                ; This should be h, not b
-  jr z, +_
-  dec a
-_:
-  ld (0D02AD9h), a
-  ld de, (0D02AD7h)
- pop af
- ret </nowiki>