Routines
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F603: Read Player Controls
Used by the routine at GameStart.
Sample Kempston (1F) or the keyboard table at Table_ControlKeyCodes into the control input bitmap. Pause (H / bit 06) waits for the key to be released and pressed again before returning.
Clear the bitmap, then try Kempston if enabled.
Read_PlayerControls F603 XOR A Clear A, then clear the control input bitmap.
F604 LD ($F5F8),A
F607 LD A,($F602) Fetch the Kempston-enabled flag. Is Kempston selected? If not, read the keyboard at Read_PlayerControls_Keyboard.
F60A OR A
F60B JR Z,Read_PlayerControls_Keyboard
F60D IN A,($1F) Read Kempston port 1F.
F60F AND %00011111 Keep bits 00–04.
F611 JR NZ,Read_PlayerControls_WriteBitmap If any direction/fire is pressed, store it at Read_PlayerControls_WriteBitmap.
Match the pressed key against Table_ControlKeyCodes and set the corresponding bit.
Read_PlayerControls_Keyboard F613 CALL Read_KeyboardControls Call Read_KeyboardControls to read a key code.
F616 OR A Was a key pressed? If not, return with the bitmap clear.
F617 RET Z
F618 LD E,$01 Start the bit mask at 01 (bit 00 = Right).
F61A LD B,$07 Load B with 07 table entries.
F61C LD HL,$F5FB Point HL at Table_ControlKeyCodes.
Scan Table_ControlKeyCodes for the pressed key and build the matching bit of ControlInputBitmap.
Read_PlayerControls_ScanTable F61F CP (HL) Does this table slot match the pressed key? If so, handle it at Read_PlayerControls_Matched.
F620 JR Z,Read_PlayerControls_Matched
F622 INC HL Advance to the next slot.
F623 SLA E Shift the bit mask left by one.
F625 DJNZ Read_PlayerControls_ScanTable Loop until the table is exhausted.
F627 XOR A Clear A (unrecognised key), then store a clear bitmap at Read_PlayerControls_WriteBitmap.
F628 JR Read_PlayerControls_WriteBitmap
Matched a control key: handle pause specially, otherwise write the bitmap.
Read_PlayerControls_Matched F62A LD A,E Keep the matched bit mask in A.
F62B BIT 6,A Is it the pause key (bit 06)? If so, debounce pause at Read_PlayerControls_PauseRelease.
F62D JR NZ,Read_PlayerControls_PauseRelease
Store the assembled control bits into ControlInputBitmap.
Read_PlayerControls_WriteBitmap F62F LD ($F5F8),A Write the control input bitmap to ControlInputBitmap.
F632 RET Return.
Wait for pause to be released, then for any key to resume.
Read_PlayerControls_PauseRelease F633 CALL Read_KeyboardControls Call Read_KeyboardControls. Is a key still held? If so, keep waiting at Read_PlayerControls_PauseRelease.
F636 OR A
F637 JR NZ,Read_PlayerControls_PauseRelease
After pause release, wait for any key before resuming play.
Read_PlayerControls_PauseResume F639 CALL Read_KeyboardControls Call Read_KeyboardControls. Has a key been pressed to resume? If not, keep waiting at Read_PlayerControls_PauseResume.
F63C OR A
F63D JR Z,Read_PlayerControls_PauseResume
F63F RET Return.
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