83Plus:Hooks:9B78 - Revision history

Michael: /* Using the Hook */

2005-04-07T03:16:33Z

‎Using the Hook

FloppusMaximus: /* Synopsis */ call addr, and links

2005-04-02T03:11:00Z

‎Synopsis: call addr, and links

JasonM at 03:09, 2 April 2005

2005-04-02T03:09:18Z

New page

[[Category:83Plus:Hooks:By Address|9B78 - Link Activity Hook]]
[[Category:83Plus:Hooks:By Name|Link Activity Hook]]
== Synopsis ==
'''Name:''' Link Activity Hook

'''Hook Pointer Block Address:''' [[83Plus:RAM:9B78|9B78]]

'''Hook Enable BCALL:''' [[83Plus:BCALLs:4F84|4F84]]

'''Hook Disable BCALL:''' [[83Plus:BCALLs:4F87|4F87]]

'''Hook Call BCALL:''' ''(Unknown)''

'''Hook Active Flag:''' 4, (iy + 33h)

'''Hook Override Flag:''' 3, (iy + 33h)

This hook is called whenever link activity is detected by the OS's interrupt handler.

== Using the Hook ==
This hook is unique in the respect that there is an OS-managed override bit. If 3, (iy + 33h) is set, the hook will not be called. This bit is called upon entry to GetKey, and is restored to it's origianl value upon exit (for the curious, iy + 33h is copied to bpSave). Consequently it is impossible (without using another hook to reset the flag during GetKey) to recieve events during GetKey; this means this hook can't be triggered throughout most parts of the TI-OS.

The hook is called whenever the interrupt detects link activity; that is, one of the two data lines has been pulled low. A contains the value the interrupt read from the link port, nothing more than the value from port 0 with the upper 6 bits masked out. All values / flags returned are ignored.

@@ Line 19: / Line 19: @@
 == Using the Hook ==
-This hook is unique in the respect that there is an OS-managed override bit. If 3, (iy + 33h) is set, the hook will not be called. This bit is called upon entry to GetKey, and is restored to it's origianl value upon exit (for the curious, iy + 33h is copied to bpSave). Consequently it is impossible (without using another hook to reset the flag during GetKey) to recieve events during GetKey; this means this hook can't be triggered throughout most parts of the TI-OS.
+This hook is unique in the respect that there is an OS-managed override bit. If 3, (iy + 33h) is set, the hook will not be called. This bit is called upon entry to GetKey, and is restored to its original value upon exit (for the curious, iy + 33h is copied to bpSave). Consequently it is impossible (without using another hook to reset the flag during GetKey) to receive events during GetKey; this means this hook can't be triggered throughout most parts of the TI-OS.
 The hook is called whenever the interrupt detects link activity; that is, one of the two data lines has been pulled low. A contains the value the interrupt read from the link port, nothing more than the value from port 0 with the upper 6 bits masked out. All values / flags returned are ignored.

@@ Line 10: / Line 10: @@
 '''Hook Disable BCALL:''' [[83Plus:BCALLs:4F87|4F87]]
-'''Hook Call BCALL:''' ''(Unknown)''
+'''Hook Call BCALL:''' [[83Plus:BCALLs:4F81|4F81]]
-'''Hook Active Flag:''' 4, (iy + 33h)
+'''Hook Active Flag:''' [[83Plus:Flags:33#Bit_4|4, (iy + 33h)]]
-'''Hook Override Flag:''' 3, (iy + 33h)
+'''Hook Override Flag:''' [[83Plus:Flags:33#Bit_3|3, (iy + 33h)]]
 This hook is called whenever link activity is detected by the OS's interrupt handler.