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Routines |
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Used by the routine at 26745.
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| 54647 | CALL 54598 | Print current control keys to screen | ||||||||||||||
| 54650 | CALL 54575 | If key-press was enqueued then load A with index of last key pressed, otherwise wait for key-press and load A with index | ||||||||||||||
| 54653 | CP 13 | If key pressed was 13 (ENTER)... | ||||||||||||||
| 54655 | RET Z | ...then return | ||||||||||||||
| 54656 | LD (54576),A | Set enqueued key index to index of key pressed | ||||||||||||||
| 54659 | LD B,5 | Load B with 5 (as there are five controls) | ||||||||||||||
| 54661 | LD HL,54894 | Point HL at start of list of current keyboard control characters | ||||||||||||||
| 54664 | LD (HL),0 | Set current keyboard control character to zero | ||||||||||||||
| 54666 | INC HL | Advance to next keyboard control character | ||||||||||||||
| 54667 | DJNZ 54664 | Decrease B (remaining number of keyboard control characters to clear) and loop back to 54664 if not zero | ||||||||||||||
| 54669 | LD BC,1280 | Load B with 5 and C with zero | ||||||||||||||
| 54672 | LD HL,54894 | Point HL at start of list of current keyboard control characters | ||||||||||||||
| 54675 | PUSH BC | Store BC (B = remaining number of controls to define, C = number of controls defined) | ||||||||||||||
| 54676 | PUSH HL | Store HL (current position in list of keyboard control characters) | ||||||||||||||
| 54677 | LD A,C | Load number of controls defined (0, 1, 2, 3 or 4) into A | ||||||||||||||
| 54678 | AND 6 | Reset all but bits 1 and 2 (to give 0, 2 or 4) | ||||||||||||||
| 54680 | ADD A,6 | Add 6 (to give 6, 8 or 10, the y-coordinates in characters of displayed keyboard controls)... | ||||||||||||||
| 54682 | LD B,A | ...and load into B | ||||||||||||||
| 54683 | LD A,C | Load A with number of controls defined (0, 1, 2, 3 or 4) | ||||||||||||||
| 54684 | AND 1 | Reset all but bit 0 (to give 0 or 1) | ||||||||||||||
| 54686 | PUSH AF | Store AF (A = bit 0 of number of controls defined) | ||||||||||||||
| 54687 | ADD A,A | Double A (to give 0 or 2)... | ||||||||||||||
| 54688 | LD C,A | ...and load into C | ||||||||||||||
| 54689 | POP AF | Restore AF (A = bit 0 of number of controls defined) | ||||||||||||||
| 54690 | PUSH AF | Store AF (A = bit 0 of number of controls defined) | ||||||||||||||
| 54691 | ADD A,C | Add C to A (to give 0 or 3) | ||||||||||||||
| 54692 | ADD A,A | Multiply A by four... | ||||||||||||||
| 54693 | ADD A,A | ...to give 0 or 12... | ||||||||||||||
| 54694 | LD C,A | ...and load into C | ||||||||||||||
| 54695 | POP AF | Restore AF (A = bit 0 of number of controls defined) | ||||||||||||||
| 54696 | ADD A,C | Add value in C to A (to give 0 or 13) | ||||||||||||||
| 54697 | ADD A,5 | Add 5 (to give 5 or 18, the x-coordinates in characters of displayed keyboard controls)... | ||||||||||||||
| 54699 | LD C,A | ...and load into C | ||||||||||||||
| 54700 | PUSH BC | Store BC (coordinates in characters of current control being defined) | ||||||||||||||
| 54701 | CALL 54148 | Load HL with attribute file address for coordinates (C, B)... | ||||||||||||||
| 54704 | LD A,(HL) | ...and set the FLASH flag for this address... | ||||||||||||||
| 54705 | OR 128 | ... | ||||||||||||||
| 54707 | LD (HL),A | ... | ||||||||||||||
| 54708 | POP BC | Restore BC (coordinates in characters of current control being defined) | ||||||||||||||
| 54709 | PUSH BC | Store BC (coordinates in characters of current control being defined) | ||||||||||||||
| 54710 | CALL 54132 | Move virtual cursor (bitmap) to display file address for coordinates x=C, y=B and load address into HL | ||||||||||||||
| 54713 | CALL 54575 | If key-press was enqueued then load A with index of last key pressed, otherwise wait for key-press and load A with index | ||||||||||||||
| 54716 | CP 32 | If key pressed was SPACE... | ||||||||||||||
| 54718 | JP Z,54744 | ...then skip ahead to 54744 | ||||||||||||||
| 54721 | CP 48 | If index of key pressed is less than 48 (i.e. below "0")... | ||||||||||||||
| 54723 | JP M,54708 | ...then jump back to 54708 (i.e. wait for next key press and try again) | ||||||||||||||
| 54726 | CP 91 | If index of key pressed is 91 or higher (i.e. above "Z")... | ||||||||||||||
| 54728 | JP P,54708 | ...then jump back to 54708 (i.e. wait for next key press and try again) | ||||||||||||||
| 54731 | CP 58 | If index of key pressed is less than 58 (i.e. "9" or below)... | ||||||||||||||
| 54733 | JP M,54744 | ...then skip ahead to 54744 | ||||||||||||||
| 54736 | CP 65 | If index of key pressed is 65 or higher (i.e. "A" or above)... | ||||||||||||||
| 54738 | JP P,54744 | ...then skip ahead to 54744 | ||||||||||||||
| 54741 | JP 54708 | Jump back to 54708 (i.e. wait for next key press and try again) | ||||||||||||||
| 54744 | CALL 54876 | Set zero flag if key pressed is already assigned to a control, otherwise reset | ||||||||||||||
| 54747 | JP Z,54708 | If key pressed is already assigned then jump back to 54708 (i.e. wait for next key press and try again) | ||||||||||||||
| 54750 | LD (23398),A | Store pressed key index at 23398 | ||||||||||||||
| 54753 | CP 32 | If key was not SPACE... | ||||||||||||||
| 54755 | JR NZ,54759 | ...then skip ahead to 54759 | ||||||||||||||
| 54757 | LD A,127 | Load A with 127 (index in character set of "SP" UDG at 65516) | ||||||||||||||
| 54759 | CALL 54097 | Print text character in A and advance bitmap virtual text cursor | ||||||||||||||
| 54762 | POP BC | Restore BC (coordinates in characters of current control being defined) | ||||||||||||||
| 54763 | CALL 54148 | Load HL with attribute file address for coordinates (C, B)... | ||||||||||||||
| 54766 | LD A,(HL) | ...and reset the FLASH flag for this address... | ||||||||||||||
| 54767 | AND 127 | ... | ||||||||||||||
| 54769 | LD (HL),A | ... | ||||||||||||||
| 54770 | POP HL | Restore HL (current position in list of keyboard control characters) | ||||||||||||||
| 54771 | LD A,(23398) | Load A with index of previously defined key... | ||||||||||||||
| 54774 | LD (HL),A | ...and store in list of keyboard control characters | ||||||||||||||
| 54775 | INC HL | Advance HL to next entry in list of keyboard control characters | ||||||||||||||
| 54776 | POP BC | Restore BC (B = remaining number of controls to define, C = number of controls defined) | ||||||||||||||
| 54777 | INC C | Increase C (number of controls defined) | ||||||||||||||
| 54778 | DJNZ 54675 | Decrease B (remaining number of controls to define) and loop back to 54675 if not zero | ||||||||||||||
| 54780 | LD B,5 | Load B with 5 (as each keyboard half-row holds five keys) | ||||||||||||||
| 54782 | LD HL,54953 | Store address of operand of instruction at 54953 (MSB of "input address" for keyboard half-row reading for LEFT)... | ||||||||||||||
| 54785 | LD (23398),HL | ...at 23398 | ||||||||||||||
| 54788 | LD HL,54894 | Point HL at start of list of current keyboard control characters | ||||||||||||||
| 54791 | PUSH BC | Store BC (B = remaining number of control keys to check) | ||||||||||||||
| 54792 | PUSH HL | Store HL (pointer to current position in list of current keyboard control characters) | ||||||||||||||
| 54793 | LD IX,54902 | Point IX at lists of characters on each keyboard half-row | ||||||||||||||
| 54797 | LD A,(HL) | Load A with current keyboard control character index | ||||||||||||||
| 54798 | LD C,0 | Set C (index in list of half-rows) to zero | ||||||||||||||
| 54800 | CP (IX+0) | If current keyboard control character index is the same as the current character in keyboard half-row groups... | ||||||||||||||
| 54803 | JR Z,54810 | ...then skip ahead to 54810 | ||||||||||||||
| 54805 | INC C | Increase C (index in list of half-rows) | ||||||||||||||
| 54806 | INC IX | Advance to next entry in list of half-rows | ||||||||||||||
| 54808 | JR 54800 | Loop back to 54800 | ||||||||||||||
| 54810 | LD A,C | Load A with index of current control key in list of half-rows | ||||||||||||||
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At this point we know the index of the current key in the list of half-rows. We now need to identify which half row it belongs to.
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| 54811 | LD B,0 | Set B (keyboard half-row index) to zero | ||||||||||||||
| 54813 | SUB 5 | If index of key in current half-row is less than 5 (i.e. key is in the current half-row)... | ||||||||||||||
| 54815 | JP M,54821 | ...then skip ahead to 54821 | ||||||||||||||
| 54818 | INC B | Increase B (keyboard half-row index) | ||||||||||||||
| 54819 | JR 54813 | Loop back to 54813 | ||||||||||||||
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The MSB in the "input address" for the various keyboard half-rows obeys the progression (254, 253, 251, 247, 239, 223, 191, 127).
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| 54821 | LD A,B | Load A with index of keyboard half-row containing current key | ||||||||||||||
| 54822 | PUSH BC | Store BC (B = index of keyboard half-row, C = index of key in list of half-rows) | ||||||||||||||
| 54823 | INC B | Increase B | ||||||||||||||
| 54824 | LD HL,128 | Load HL with 128 | ||||||||||||||
| 54827 | ADD HL,HL | Double value in HL | ||||||||||||||
| 54828 | DJNZ 54827 | Decrease B (index of keyboard half-row) and loop back to 54827 if not zero | ||||||||||||||
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HL now contains the value (128 × 2n) where n is the (1-based) index of the relevant half-row. H contains (2m, where m is the (zero-based) index of the relevant half-row.
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| 54830 | LD A,255 | Load A with 255 | ||||||||||||||
| 54832 | SUB H | Subtract H (2m) to give MSB of input address for relevant half-row | ||||||||||||||
| 54833 | LD HL,(23398) | Load HL with address of operand of instruction to modify (54953)... | ||||||||||||||
| 54836 | LD (HL),A | ...and set operand to value in A | ||||||||||||||
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Next we need to modify the second part of the opcode for the instruction that checks the set bit in A to determine which key in the half-row was pressed. The range of opcode values are:
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| 54837 | INC HL | Advance HL by four bytes to operand of instruction at 54956... | ||||||||||||||
| 54838 | INC HL | ... | ||||||||||||||
| 54839 | INC HL | ... | ||||||||||||||
| 54840 | INC HL | ... | ||||||||||||||
| 54841 | LD (23398),HL | ...and store at 23398 | ||||||||||||||
| 54844 | POP BC | Restore BC (B = index of keyboard half-row, C = index of key in list of half-rows) | ||||||||||||||
| 54845 | LD A,B | Load B with five times index of keyboard half-row (value currently in B)... | ||||||||||||||
| 54846 | ADD A,A | ... | ||||||||||||||
| 54847 | ADD A,A | ... | ||||||||||||||
| 54848 | ADD A,B | ... | ||||||||||||||
| 54849 | LD B,A | ... (B is now 0, 5, 10, 15, 20, 25, 30 or 35) | ||||||||||||||
| 54850 | LD A,C | Load A with index of key in list of half-rows... | ||||||||||||||
| 54851 | SUB B | ...and subtract B (5 times index of half-row) to give index of key within current half-row | ||||||||||||||
| 54852 | ADD A,A | Multiply this index by 8 (opcode interval between successive BIT n,A and BIT n+1,A instructions)... | ||||||||||||||
| 54853 | ADD A,A | ... | ||||||||||||||
| 54854 | ADD A,A | ... | ||||||||||||||
| 54855 | ADD A,71 | ...and add 71 (opcode for BIT 0,A) | ||||||||||||||
| 54857 | LD HL,(23398) | Load HL with address of operand / opcode for BIT n,A instruction... | ||||||||||||||
| 54860 | LD (HL),A | ...and set "n" accordingly | ||||||||||||||
| 54861 | LD BC,5 | Advance HL by five bytes to operand of next LD B,x instruction (i.e. MSB of "input address" for next control)... | ||||||||||||||
| 54864 | ADD HL,BC | ... | ||||||||||||||
| 54865 | LD (23398),HL | ...and store at 23398 | ||||||||||||||
| 54868 | POP HL | Restore HL (pointer to current position in list of current keyboard control characters, PUSHed at 54792) | ||||||||||||||
| 54869 | INC HL | Advance HL to next keyboard control character | ||||||||||||||
| 54870 | POP BC | Store BC (B = remaining number of control keys to check, PUSHed at 54791) | ||||||||||||||
| 54871 | DJNZ 54791 | Decrease B (remaining number of control keys to check) and loop back to 54791 for next control key if not zero | ||||||||||||||
| 54873 | JP 55138 | Display "PRESS FIRE TO CONTINUE" window and wait for fire to be pressed and return | ||||||||||||||
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