Difference between revisions of "83Plus:BCALLs:45CD"
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Calc84maniac (Talk | contribs) (Carry flag output) |
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=== Outputs === | === Outputs === | ||
| − | * A | + | * Carry flag set if menu requires further keypresses. |
| + | * Carry flag reset if a final keypress is returned in A (might be the same as the original keypress) | ||
=== Registers Destroyed === | === Registers Destroyed === | ||
| Line 20: | Line 21: | ||
Calling this immediately after [[83Plus:BCALLs:4972|GetKey]] will allow OS menus to appear during execution of your program. The output of this routine may be an unprocessed key or it may be the result of a menu action. For instance if a=kenter was sent to this routine while entry 2 is highlighted in the Draw menu, the output of this routine would be a=kLine. | Calling this immediately after [[83Plus:BCALLs:4972|GetKey]] will allow OS menus to appear during execution of your program. The output of this routine may be an unprocessed key or it may be the result of a menu action. For instance if a=kenter was sent to this routine while entry 2 is highlighted in the Draw menu, the output of this routine would be a=kLine. | ||
| − | == | + | == Examples == |
| + | getmenukeyloop: | ||
| + | B_CALL GetKey | ||
| + | B_CALL PullDownChk | ||
| + | jr c,getmenukeyloop ;Loop if more keypresses are needed | ||
| + | ;After the loop, A holds a keypress value | ||
| + | |||
ld a,kDraw | ld a,kDraw | ||
B_CALL PullDownChk ;on LCD the draw menu should be visable | B_CALL PullDownChk ;on LCD the draw menu should be visable | ||
Latest revision as of 20:35, 22 December 2010
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Synopsis
Official Name: PullDownChk
BCALL Address: 45CD
Checks for and processes any keys relating to menus.
Inputs
- A = key press
Outputs
- Carry flag set if menu requires further keypresses.
- Carry flag reset if a final keypress is returned in A (might be the same as the original keypress)
Registers Destroyed
- unknown
Comments
Calling this immediately after GetKey will allow OS menus to appear during execution of your program. The output of this routine may be an unprocessed key or it may be the result of a menu action. For instance if a=kenter was sent to this routine while entry 2 is highlighted in the Draw menu, the output of this routine would be a=kLine.
Examples
getmenukeyloop: B_CALL GetKey B_CALL PullDownChk jr c,getmenukeyloop ;Loop if more keypresses are needed ;After the loop, A holds a keypress value
ld a,kDraw B_CALL PullDownChk ;on LCD the draw menu should be visable ld a,kDown B_CALL PullDownChk ;cursor should move from entry 1 to entry 2 ld a,kEnter B_CALL PullDownChk ;output of routine should be kLine
