.MoveIconBarPointer ; This routine is called every VBlank and manages the ; movement of the icon bar pointer and choosing icon bar ; buttons ; ; We start by updating a couple of counters that are ; only used in the PAL version, and which are ignored in ; the NTSC version DEC pointerTimer ; Decrement the pointer timer ; ; This timer is used in the PAL version to detect the B ; button being pressed twice in quick succession ; ; The pointer timer is updated in the NTSC version but ; is otherwise ignored IF _PAL BNE mbar1 ; If the pointer timer has not reached zero, jump to ; mbar1 to skip the following instruction LSR pointerTimerB ; Zero pointerTimerB (this works because pointerTimerB ; is only ever 0 or 1) ; ; The pointerTimerB timer is used in the PAL version to ; detect the B button being pressed twice in quick ; succession, so zeroing it indicates that the timer has ; run down before the B button was pressed for the ; second time, so this can't be a double-tap ; ; The NTSC version does away with this variable ; altogether, as well as ignoring pointerTimer .mbar1 ENDIF BPL mbar2 ; If pointerTimer is positive, jump to mbar2 to skip ; the following instruction INC pointerTimer ; Increment pointerTimer so it doesn't decrement past ; zero .mbar2 DEC pointerMoveCounter ; Decrement the pointer move counter, which is used to ; keep track of whether the icon bar pointer is moving ; between two buttons (if the counter is non-zero, then ; the pointer is currently moving between two buttons) BPL mbar3 ; If pointerMoveCounter is positive, jump to mbar3 to ; skip the following instruction INC pointerMoveCounter ; Increment pointerMoveCounter so it doesn't decrement ; past zero .mbar3 ; We now confirm that there is an icon bar for us to ; manage (if not, we leave the subroutine at this point) LDA screenFadedToBlack ; If bit 7 of screenFadedToBlack is set then we have BMI hipo2 ; already faded the screen to black, so jump to hipo2 ; to clear the icon button choice and hide the icon bar ; pointer LDA showIconBarPointer ; If showIconBarPointer = 0 then the icon bar pointer BEQ HideIconBarPointer ; should be hidden, so jump to HideIconBarPointer to do ; just that ; If we get here then the icon bar pointer is visible, ; so we now need to process any movement before drawing ; the pointer in its new location ; ; The pointer coordinates are stored in xIconBarPointer ; and yIconBarPointer, though note that the x-coordinate ; in xIconBarPointer is multiplied by 5 to get the final ; pixel x-coordinate (the yIconBarPointer value, on the ; other hand, contains a pixel coordinate from the off) ; ; The movement of the pointer is stored in xPointerDelta ; as a delta, which is set later in the routine ; according to the buttons being pressed on the ; controller ; ; The xPointerDelta variable is set to zero by default, ; and is only non-zero if the previous call to this ; routine detected the correct movement buttons LDA xPointerDelta ; Set xIconBarPointer = xIconBarPointer + xPointerDelta CLC ; ADC xIconBarPointer ; So this updates the x-coordinate of the icon bar STA xIconBarPointer ; to move it in the direction of xPointerDelta (which ; was set to -1, 0 or +1 depending on which directional ; keys were being pressed the last time we were here) AND #3 ; If xIconBarPointer mod 4 is non-zero, jump to mbar9 to BNE mbar9 ; skip updating the movement delta in xPointerDelta, so ; we only scan for movement keys every four movements of ; the pointer (this ensures that when a movement starts, ; it runs for four VBlanks without being interrupted, so ; the pointer keeps moving towards the next button, one ; step for each VBlank) ; ; In other words, when xIconBarPointer mod 4 is 0, the ; pointer is on a button, while other values mean it is ; between buttons ; If we get here then the movement has been applied for ; four VBlanks, so the pointer has now moved onto the ; next button LDA #0 ; Set xPointerDelta = 0 so the pointer is not moving by STA xPointerDelta ; default, though we now change that if the movement ; buttons are being pressed LDA pointerMoveCounter ; If pointerMoveCounter is non-zero then we are already BNE mbar9 ; moving the pointer between two buttons, so jump to ; mbar9 to leave xPointerDelta at zero and ignore any ; button presses, as we need to finish the jump from one ; button to another before we can move it again ; ; This ensures that once we start a movement between ; icon bar buttons, we wait until pointerMoveCounter ; VBlanks have passed before listening for the next move ; ; pointerMoveCounter is set to 12 at the start of each ; move, so we spend the first four VBlanks moving the ; pointer, then xPointerDelta is zeroed above, and then ; we wait for another eight VBlanks before listening for ; button presses again ; ; This gives the icon bar pointer a stepped movement ; that jumps from button to button if the left or right ; buttons are held down LDA controller1B ; If the B button is not being pressed on controller 1 ORA numberOfPilots ; and the game is configured for one pilot, jump to BPL mbar9 ; mbar9 to skip updating the movement delta in ; xPointerDelta, as in one-pilot mode we can only move ; the icon bar pointer when the B button is held down ; ; If the game is configured for two pilots, we always ; pass through this branch as numberOfPilots = 1, so ; we don't need the B button to be held down when there ; are two pilots ; We now process the left button, which moves the icon ; bar pointer to the left LDX controller1Left ; If the left button on controller 1 is being pressed, BMI mbar4 ; jump to mbar4 to set xPointerDelta to -1 LDA #0 ; Otherwise reset controller1Left to 0 to clear out the STA controller1Left ; left button history in the controller variable, to ; make the logic below slightly simpler (see mbar13) JMP mbar6 ; Jump to mbar6 to check for the right button .mbar4 ; If we get here then the left button is being pressed ; and X contains the value of controller1Left LDA #$FF ; Set A = -1 to set as the value of xPointerDelta CPX #%10000000 ; If the left button has just been pressed but wasn't BNE mbar5 ; being pressed before, keep going, otherwise jump to ; mbar5 to skip the following ; The following is therefore only run when we first ; press the left button LDX #12 ; The left button was just pressed but wasn't being STX pointerMoveCounter ; pressed before, so set pointerMoveCounter to 12 so it ; can count down to zero, during which time we don't ; check for any more directional button presses (as the ; pointer will be moving between icon bar buttons) .mbar5 STA xPointerDelta ; Set xPointerDelta = -1, so the pointer moves to the ; left .mbar6 ; We now process the right button, which moves the icon ; bar pointer to the right LDX controller1Right ; If the right button on controller 1 is being pressed, BMI mbar7 ; jump to mbar7 to set xPointerDelta to 1 LDA #0 ; Reset controller1Right to 0 to clear out the right STA controller1Right ; button history in the controller variable, to ; make the logic below slightly simpler (see mbar13) JMP mbar9 ; Jump to mbar9 to move on to clipping the pointer's ; x-coordinate .mbar7 LDA #1 ; Set A = 1 to set as the value of xPointerDelta CPX #%10000000 ; If the right button has just been pressed but wasn't BNE mbar8 ; being pressed before, keep going, otherwise jump to ; mbar8 to skip the following ; The following is therefore only run when we first ; press the right button LDX #12 ; The right button was just pressed but wasn't being STX pointerMoveCounter ; pressed before, so set pointerMoveCounter to 12 so it ; can count down to zero, during which time we don't ; check for any more directional button presses (as the ; pointer will be moving between icon bar buttons) .mbar8 STA xPointerDelta ; Set xPointerDelta = 1, so the pointer moves to the ; left .mbar9 ; We now clip the x-coordinate of the pointer to ensure ; it is in the range 0 to 44 (which equates to a pixel ; range of 0 to 44 * 5 = 220) LDA xIconBarPointer ; If xIconBarPointer < 128, jump to mbar10 to skip the BPL mbar10 ; following LDA #0 ; If we get here then xIconBarPointer >= 128, so set STA xPointerDelta ; xPointerDelta = 0 to stop the pointer from moving BEQ mbar11 ; Jump to mbar11 with A = 0 to set xIconBarPointer = 0, ; so the value of xIconBarPointer wraps around to zero ; if it goes above 127 (this BEQ is effectively a JMP ; as A is always zero) .mbar10 CMP #45 ; If xIconBarPointer < 45, jump to mbar11 to move on to BCC mbar11 ; the next set of checks LDA #0 ; If we get here then 45 <= xIconBarPointer < 127, so STA xPointerDelta ; set xPointerDelta = 0 to stop the pointer from moving LDA #44 ; Set A = 44 to store in xIconBarPointer, so the value ; of xIconBarPointer never gets above 44 .mbar11 STA xIconBarPointer ; Set xIconBarPointer to the clipped value in A, so ; xIconBarPointer is in the range 0 to 44 ; We now draw the icon bar pointer in either the up or ; down position ; ; We draw it in the up position if any of the following ; are true: ; ; * xIconBarPointer mod 4 is non-zero (in which case ; we know that the pointer is moving between ; buttons) ; ; * xPointerDelta is non-zero (so the pointer only ; ever moves when it is in the up position) ; ; * The B button is being pressed (which is the button ; we press to lift the pointer up) ; ; * The Select button is being pressed (so the pointer ; jumps up when we choose an icon from the icon bar ; with Select) ; ; Otherwise we draw it in the down position LDA xIconBarPointer ; If xIconBarPointer mod 4 is non-zero or xPointerDelta AND #3 ; is non-zero, then as noted above, this means that the ORA xPointerDelta ; pointer is between buttons, so jump to mbar12 to draw BNE mbar12 ; the icon bar pointer in the up position LDA controller1B ; If the B button is being pressed, jump to mbar12 to BMI mbar12 ; draw the icon bar pointer in the up position (this LDA controller1B ; comparison is repeated, but that doesn't seem to have BMI mbar12 ; any effect) LDA controller1Select ; If the Select button is being pressed, jump to mbar12 BNE mbar12 ; to draw the icon bar pointer in the up position ; If we get here then the B button is not being pressed, ; so we draw the icon bar pointer in the down position, ; so it looks as if it goes around the bottom of the ; button ; ; The pointer is made up of the following sprites, which ; are ordered in a clockwise fashion: ; ; * Sprite 1 in the top-left ; * Sprite 2 in the top-right ; * Sprite 3 in the bottom-right ; * Sprite 4 in the bottom-left ; ; The value of yIconBarPointer contains the y-coordinate ; of the icon bar, which is 148 when there is a ; dashboard or this is the Game Over screen, or 204 ; otherwise ; ; The value of xIconBarPointer is in the range 0 to 44, ; which represents the icon bar with buttons on each ; multiple of 4 LDA #251 ; Set the pattern number for the sprites 1 and 2 to STA pattSprite1 ; pattern 251, so the top part of the pointer appears to STA pattSprite2 ; go behind the button LDA yIconBarPointer ; Set the y-coordinate of the top of the pointer in CLC ; sprites 1 and 2 to yIconBarPointer + 11, so the ADC #11+YPAL ; pointer is drawn in the down position (three pixels STA ySprite1 ; lower down the screen than the up position) STA ySprite2 LDA xIconBarPointer ; Set A = 6 + xIconBarPointer * 4 + xIconBarPointer ASL A ; = 6 + 5 * xIconBarPointer ASL A ; ADC xIconBarPointer ; As noted above, xIconBarPointer is in the range 0 to ADC #6 ; 44, so the pixel x-coordinate of the pointer is in ; the range 6 to 226 ; We now use A as the x-coordinate of the bottom-left ; corner of the four-sprite pointer by setting the ; sprite's coordinates as follows (with the bottom ; sprites being spread out slightly more than the top ; sprites) STA xSprite4 ; Set the x-coordinate of sprite 4 in the bottom-left ; of the pointer to A ADC #1 ; Set the x-coordinate of sprite 1 in the top-left of STA xSprite1 ; the pointer to A + 1 ADC #13 ; Set the x-coordinate of sprite 2 in the top-right of STA xSprite2 ; the pointer to A + 14 ADC #1 ; Set the x-coordinate of sprite 3 in the bottom-right STA xSprite3 ; of the pointer to A + 15 LDA yIconBarPointer ; Set the y-coordinate of the bottom of the pointer in CLC ; sprites 3 and 4 to yIconBarPointer + 19, so the ADC #19+YPAL ; pointer is drawn in the down position (three pixels STA ySprite4 ; lower down the screen than the up position) STA ySprite3 LDA xIconBarPointer ; If xIconBarPointer is non-zero then jump to mbar13 BNE mbar13 ; (though this has no effect as that's what we're about ; to do anyway) JMP mbar13 ; Jump to mbar13 to continue checking for button presses .mbar12 ; If we get here then the B button is being pressed, so ; we draw the icon bar pointer in the up position, so it ; looks as if can be moved left or right without being ; blocked by the buttons ; ; The pointer is made up of the following sprites, which ; are ordered in a clockwise fashion: ; ; * Sprite 1 in the top-left ; * Sprite 2 in the top-right ; * Sprite 3 in the bottom-right ; * Sprite 4 in the bottom-left ; ; The value of yIconBarPointer contains the y-coordinate ; of the icon bar, which is 148 when there is a ; dashboard or this is the Game Over screen, or 204 ; otherwise ; ; The value of xIconBarPointer is in the range 0 to 44, ; which represents the icon bar with buttons on each ; multiple of 4 LDA #252 ; Set the pattern number for the sprites 1 and 2 to STA pattSprite1 ; pattern 252, so the top part of the pointer appears to STA pattSprite2 ; pop up from behind the top of the button LDA yIconBarPointer ; Set the y-coordinate of the top of the pointer in CLC ; sprites 1 and 2 to yIconBarPointer + 8, so the ADC #8+YPAL ; pointer is drawn in the up position (three pixels STA ySprite1 ; higher up the screen than the down position) STA ySprite2 LDA xIconBarPointer ; Set A = 6 + xIconBarPointer * 4 + xIconBarPointer ASL A ; = 6 + 5 * xIconBarPointer ASL A ; ADC xIconBarPointer ; As noted above, xIconBarPointer is in the range 0 to ADC #6 ; 44, so the pixel x-coordinate of the pointer is in ; the range 6 to 226 ; We now use A as the x-coordinate of the bottom-left ; corner of the four-sprite pointer by setting the ; sprite's coordinates as follows (with the bottom ; sprites being spread out slightly more than the top ; sprites) STA xSprite4 ; Set the x-coordinate of sprite 4 in the bottom-left ; of the pointer to A ADC #1 ; Set the x-coordinate of sprite 1 in the top-left of STA xSprite1 ; the pointer to A + 1 ADC #13 ; Set the x-coordinate of sprite 2 in the top-right of STA xSprite2 ; the pointer to A + 14 ADC #1 ; Set the x-coordinate of sprite 3 in the bottom-right STA xSprite3 ; of the pointer to A + 15 LDA yIconBarPointer ; Set the y-coordinate of the bottom of the pointer in CLC ; sprites 3 and 4 to yIconBarPointer + 16, so the ADC #16+YPAL ; pointer is drawn in the up position (three pixels STA ySprite4 ; higher up the screen than the down position) STA ySprite3 .mbar13 ; We now check the controller buttons to see if an icon ; bar button has been chosen ; ; The logic for the PAL version is rather more ; convoluted than the NTSC version LDA controller1Left ; If none of the directional buttons are being pressed, ORA controller1Right ; jump to mbar14 to skip the following ORA controller1Up ORA controller1Down BPL mbar14 LDA #0 ; At least one of the directional buttons is being STA pointerPressedB ; pressed, so set pointerPressedB = 0 so we don't look ; for a double-tap of the B button .mbar14 LDA controller1Select ; If the Select button has just been pressed but wasn't AND #%11110000 ; being pressed before, jump to mbar17 to choose the CMP #%10000000 ; button under the pointer BEQ mbar17 LDA controller1B ; If the B button has just been pressed but wasn't being AND #%11000000 ; pressed before, keep going, otherwise jump to mbar15 CMP #%10000000 ; to skip the following BNE mbar15 LDA #30 ; The B button has just been pressed but wasn't being STA pointerPressedB ; pressed before, so set pointerPressedB to a non-zero ; value so we start looking for a double-tap of the B ; button ; ; This value of A also ensures that we jump to mbar18 ; in the next comparison, as %01000000 does not match ; 30, so this essentially sets pointerPressedB to a ; non-zero value and then moves on to the next VBlank, ; leaving the non-zero value to be picked up in a future ; VBlank below .mbar15 CMP #%01000000 ; If the B button was being pressed but has just been BNE mbar18 ; released, keep going, otherwise jump to mbar18 to move ; onto the next set of checks IF _NTSC LDA pointerPressedB ; If pointerPressedB = 0 then jump to mbar18 to move BEQ mbar18 ; onto the next set of checks ; If we get here then pointerPressedB is non-zero, so we ; know the B button was pressed and released in a ; previous VBlank, and we know that in this VBlank, the ; B button was being pressed but has just been released, ; so that's a double-tap on the B button ; ; This is one of the ways of choosing an icon bar icon, ; so fall through into mbar17 to choose the button under ; the pointer ELIF _PAL LDA pointerPressedB ; If pointerPressedB is non-zero then the B button was BNE mbar16 ; tapped and released in a previous VBlank, so jump to ; mbar16 to potentially process a double-tap on the B ; button STA pointerTimerB ; Otherwise zero pointerTimerB, so pointerTimerB is zero ; if we are not looking for a double-tap BEQ mbar18 ; Jump to mbar18 to move on to the next set of checks ; (this BEQ is effectively a JMP as A is always zero) .mbar16 ; If we get here then the B button was tapped and ; released in a previous VBlank LDA #40 ; Set pointerTimer = 40 so it counts down over the next STA pointerTimer ; 40 VBlanks, zeroing pointerTimerB if it runs out ; before the second tap on the B button is detected LDA pointerTimerB ; If pointerTimerB = 1 then we are already looking for BNE mbar17 ; the second tap of a double-tap on the B button, which ; we just found, so jump to mbar17 to choose the button ; under the pointer INC pointerTimerB ; Otherwise increment pointerTimerB to 1 and skip the BNE mbar18 ; following instruction, so we will be on the lookout ; for the second tap of the B button in future VBlanks ENDIF .mbar17 IF _PAL LSR pointerTimerB ; Set pointerTimerB = 0 as we have now chosen an icon ; bar button, so we don't need to check for a double-tap ; on the B button any more ENDIF ; If we get here then we have chosen a button on the ; icon bar, so we update iconBarChoice accordingly LDA xIconBarPointer ; Set Y to the button number that the icon bar pointer LSR A ; is over LSR A TAY LDA (barButtons),Y ; Set iconBarChoice to the Y-th entry from the button STA iconBarChoice ; table for this icon bar to indicate that this icon bar ; button has been selected .mbar18 ; Finally, we check to see if the Start button has been ; tapped, and if so, we record that as an iconBarChoice ; of 80 LDA controller1Start ; If the Start button on controller 1 was being held AND #%11000000 ; down (bit 6 is set) but is no longer being held down CMP #%01000000 ; (bit 7 is clear) then keep going, otherwise jump to BNE mbar19 ; mbar19 LDA #80 ; Set iconBarChoice to indicate that the Start button STA iconBarChoice ; has been pressed .mbar19 RTS ; Return from the subroutineName: MoveIconBarPointer [Show more] Type: Subroutine Category: Icon bar Summary: Move the sprites that make up the icon bar pointer and record any choices Deep dive: Sprite usage in NES EliteContext: See this subroutine in context in the source code References: This subroutine is called as follows: * NMI calls MoveIconBarPointer
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Subroutine HideIconBarPointer (category: Icon bar)
Clear the icon bar choice and hide the icon bar pointer
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Configuration variable YPAL = 6 AND _PAL
A margin of 6 pixels that is applied to a number of y-coordinates for the PAL version only (as the PAL version has a taller screen than NTSC)
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Variable barButtons in workspace ZP
The address of the list of button numbers in the iconBarButtons table for the current icon bar
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Variable controller1B in workspace WP
A shift register for recording presses of the B button on controller 1
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Variable controller1Down in workspace WP
A shift register for recording presses of the down button on controller 1
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Variable controller1Left in workspace WP
A shift register for recording presses of the left button on controller 1
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Variable controller1Right in workspace WP
A shift register for recording presses of the right button on controller 1
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Variable controller1Select in workspace WP
A shift register for recording presses of the Select button on controller 1
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Variable controller1Start in workspace WP
A shift register for recording presses of the Start button on controller 1
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Variable controller1Up in workspace WP
A shift register for recording presses of the up button on controller 1
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Entry point hipo2 in subroutine HideIconBarPointer (category: Icon bar)
Clear the icon button choice and hide the icon bar pointer
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Variable iconBarChoice in workspace WP
The number of the icon bar button that's just been selected
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Label mbar1 is local to this routine
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Label mbar10 is local to this routine
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Label mbar11 is local to this routine
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Label mbar12 is local to this routine
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Label mbar13 is local to this routine
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Label mbar14 is local to this routine
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Label mbar15 is local to this routine
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Label mbar16 is local to this routine
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Label mbar17 is local to this routine
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Label mbar18 is local to this routine
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Label mbar19 is local to this routine
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Label mbar2 is local to this routine
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Label mbar3 is local to this routine
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Label mbar4 is local to this routine
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Label mbar5 is local to this routine
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Label mbar6 is local to this routine
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Label mbar7 is local to this routine
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Label mbar8 is local to this routine
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Label mbar9 is local to this routine
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Variable numberOfPilots in workspace WP
A flag to determine whether the game is configured for one or two pilots
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Variable pattSprite1 in workspace Sprite buffer
Pattern number for sprite 1
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Variable pattSprite2 in workspace Sprite buffer
Pattern number for sprite 2
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Variable pointerMoveCounter in workspace WP
The position of the icon bar pointer as it moves between icons, counting down from 12 (at the start of the move) to 0 (at the end of the move)
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Variable pointerPressedB in workspace WP
Controls whether the MoveIconBarPointer routine looks for a second tap of the B button when trying to detect a double-tap on the B button
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Variable pointerTimer in workspace WP
A timer that counts down by 1 on each call to the MoveIconBarPointer routine, so that a double-tap on the B button can be interpreted as such
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Variable pointerTimerB in workspace WP
A timer used in the PAL version to detect the B button being pressed twice in quick succession (a double-tap)
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Variable screenFadedToBlack in workspace WP
Records whether the screen has been faded to black
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Variable showIconBarPointer in workspace WP
Controls whether to show the icon bar pointer
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Variable xIconBarPointer in workspace WP
The x-coordinate of the icon bar pointer
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Variable xPointerDelta in workspace WP
The direction in which the icon bar pointer is moving, expressed as a delta to add to the x-coordinate of the pointer sprites
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Variable xSprite1 in workspace Sprite buffer
Screen x-coordinate for sprite 1
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Variable xSprite2 in workspace Sprite buffer
Screen x-coordinate for sprite 2
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Variable xSprite3 in workspace Sprite buffer
Screen x-coordinate for sprite 3
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Variable xSprite4 in workspace Sprite buffer
Screen x-coordinate for sprite 4
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Variable yIconBarPointer in workspace WP
The y-coordinate of the icon bar pointer
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Variable ySprite1 in workspace Sprite buffer
Screen y-coordinate for sprite 1
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Variable ySprite2 in workspace Sprite buffer
Screen y-coordinate for sprite 2
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Variable ySprite3 in workspace Sprite buffer
Screen y-coordinate for sprite 3
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Variable ySprite4 in workspace Sprite buffer
Screen y-coordinate for sprite 4