WikiTI - User contributions [en]

83Plus:Hooks:9B8C

2008-02-26T13:41:51Z

HQAT:

[[Category:83Plus:Hooks:By_Name|Homescreen Hook]] [[Category:83Plus:Hooks:By_Address|9B8C - Homescreen Hook]]
== Synopsis ==
'''Name:''' Homescreen

'''Hook Pointer Block Address:''' [[83Plus:RAM:9B8C|9B8C]]

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

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

'''Hook Call BCALL:''' ''(none known)''

'''Hook Active Flag:''' [[83Plus:Flags:34#Bit_4|4, (iy + 34h)]]

This hook is called when various events occur on the homescreen.

== Using the Hook ==
These different values, passed in A, determine what the hook should do.
* 0: The calculator is displaying a result.
** [[83Plus:RAM:8478|OP1]] = the value to display
** You can change the value in OP1 to display something different, which will not affect the value stored to Ans.
** If you want to display something wider than the screen, you must also write the formatted string to [[83Plus:RAM:97B1|fmtString]].
** Return NZ and TIOS will not display anything.
* 1: A key was pressed at the homescreen.
** B = keycode
** Change B to change the key that appears to be pressed.
** Return NZ to ignore the keypress.
* 2: An expression was entered to be evaluated.
** OP1 contains prgm!.
** To retreive the expression to be evaluated use prgm#.
** Return NZ to cancel running the program.
* 3: Changing context to the homescreen.
** B = previous context value
** You should always return Z in this case.

== Example ==
The following code will display a random number as the result of any calculation.

<nowiki>HomescreenHook:
.db 83h ; Required for all hooks
or a ; are we in condition 0 (display value?)
jr nz,ReturnZ
B_CALL Random ; change our output value to a random #
ReturnZ:
cp a ; set zero condition
ret</nowiki>

== Credits and Contributions ==
* '''Michael Vincent:''' Analysis and writing the most amazingly cool homescreen hacks I've seen yet.

83Plus:Hooks:9B8C

2008-02-26T13:23:28Z

HQAT:

[[Category:83Plus:Hooks:By_Name|Homescreen Hook]] [[Category:83Plus:Hooks:By_Address|9B8C - Homescreen Hook]]
== Synopsis ==
'''Name:''' Homescreen

'''Hook Pointer Block Address:''' [[83Plus:RAM:9B8C|9B8C]]

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

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

'''Hook Call BCALL:''' ''(none known)''

'''Hook Active Flag:''' [[83Plus:Flags:34#Bit_4|4, (iy + 34h)]]

This hook is called when various events occur on the homescreen.

== Using the Hook ==
These different values, passed in A, determine what the hook should do.
* 0: The calculator is displaying a result.
** [[83Plus:RAM:8478|OP1]] = the value to display
** You can change the value in OP1 to display something different, which will not affect the value stored to Ans.
** If you want to display something wider than the screen, you must also write the formatted string to [[83Plus:RAM:97B1|fmtString]].
** Return NZ and TIOS will not display anything.
* 1: A key was pressed at the homescreen.
** B = keycode
** Change B to change the key that appears to be pressed.
** Return NZ to ignore the keypress.
* 2: An expression was entered to be evaluated.
** OP1 contains the name of the entry, prgm#.
** To retreive the expression to be evaluated use prgm!.
** Return NZ to cancel running the program.
* 3: Changing context to the homescreen.
** B = previous context value
** You should always return Z in this case.

== Example ==
The following code will display a random number as the result of any calculation.

<nowiki>HomescreenHook:
.db 83h ; Required for all hooks
or a ; are we in condition 0 (display value?)
jr nz,ReturnZ
B_CALL Random ; change our output value to a random #
ReturnZ:
cp a ; set zero condition
ret</nowiki>

== Credits and Contributions ==
* '''Michael Vincent:''' Analysis and writing the most amazingly cool homescreen hacks I've seen yet.