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open-roms/c64/kernal/keyboard/scnkey.s
T

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ArmAsm

//
// Official Kernal routine, described in:
//
// - [RG64] C64 Programmer's Reference Guide - page 295
// - [CM64] Compute's Mapping the Commodore 64 - page 220
//
// CPU registers that has to be preserved (see [RG64]): none
//
// Variables used:
// - KEYTAB - keyboard matrix pointer
// - DELAY - counter for first delay between key repeats
// - KOUNT - counter for next delays between key repeats
// - SHFLAG - SHIFT / CTRL / VENDOR keypress status
// - NDX - number of characters in keyboard buffer
// - XMAX - maximum size of keyboard buffer
// - LSTX - matrix coordinate of last pressed key
// - LSTSHF - previous status of SHFLAG
// - MODE - flag, whether charset toggle (SHIFT+VENDOR) is allowed
// - RPTFLG - whether key repeat is allowed
#if !CONFIG_LEGACY_SCNKEY
// Routine takes some ideas from TWW/CTR proposal, see here:
// - http://codebase64.org/doku.php?id=base:scanning_the_keyboard_the_correct_and_non_kernal_way
SCNKEY:
#if CONFIG_KEYBOARD_C65 && CONFIG_MB_MEGA_65
// Idea by Paul Gardner-Stephen
lda VIC_XPOS // check raster X position
cmp VIC_XPOS // if it changes, we are on a MEGA65 with VIC-IV registers already visible
bne scnkey_viciv_mode
// We are on machine that is not in VIC-IV IO mode, so try enabling it (harmless on C64/C65)
// If we are on a C65 (or MEGA65 with C65 VIC-III IO mode selected), the above test would
// have failed, but we could already be in C65 IO mode. In that case, this will disable C65 IO
// mode when done. This is not ideal, but as MEGA65s start C65 mode with VIC-IV IO mode
// selected anyway, it should not be a big problem in practice.
lda #$A5
sta VIC_KEY
lda #$96
sta VIC_KEY
jsr scnkey_viciv_mode
sta VIC_KEY
rts
scnkey_viciv_mode:
#endif
// Prepare for SHFLAG update
lda SHFLAG
sta LSTSHF
lda #$00
sta SHFLAG
#if !CONFIG_JOY2_CURSOR && CONFIG_KEY_FAST_SCAN
// Check for any activity - speed optimization, but cannot be done
// that early if we are to scan the joystick #2
ldx #$00
stx CIA1_PRA // connect all the rows
#if CONFIG_KEYBOARD_C128
stx VIC_XSCAN
#endif
dex // puts $FF
cpx CIA1_PRB
beq scnkey_no_keys
#endif
// Retrieve SHIFT / VENDOR / CTRL / ALT / CAPS LOCK status
#if CONFIG_KEYBOARD_C128_CAPS_LOCK
// First check if this is really a C128 - to avoid false positive
ldx #$00
stx VIC_XSCAN
dex // puts $FF
cpx VIC_XSCAN
beq !+ // branch if C64, C128 will keep some bits cleared
lda CPU_R6510
and #$40
bne !+ // branch if no CAPS LOCK
lda #KEY_CAPS_LOCK
sta SHFLAG
!:
#if !CONFIG_KEYBOARD_C128
stx VIC_XSCAN // disconnect C128 keys if no C128 keyboard is supported
#endif
#endif
#if CONFIG_KEYBOARD_C65_CAPS_LOCK
lda C65_EXTKEYS_PR
and #$01
bne !+ // branch if no CAPS LOCK
lda #KEY_CAPS_LOCK
sta SHFLAG
!:
#if !CONFIG_KEYBOARD_C65
ldx #$FF
stx C65_EXTKEYS_PR // disconnect C128 keys if no C128 keyboard is supported
#endif
#endif
ldy #(__kb_matrix_bucky_confmask_end - kb_matrix_bucky_confmask - 1)
scnkey_bucky_loop:
lda kb_matrix_bucky_confmask, y
sta CIA1_PRA
#if CONFIG_KEYBOARD_C128
lda kb_matrix_bucky_confmask_c128, y
sta VIC_XSCAN
#endif
#if CONFIG_KEYBOARD_C65
lda kb_matrix_bucky_confmask_c65, y
sta C65_EXTKEYS_PR
#endif
lda kb_matrix_bucky_testmask, y
and CIA1_PRB
bne !+ // branch if not pressed
lda SHFLAG
ora kb_matrix_bucky_shflag, y
sta SHFLAG
!:
dey
bpl scnkey_bucky_loop
// Set KEYTAB vector
jsr via_keylog // XXX for some CPUs we have indirect jsr
#if CONFIG_JOY2_CURSOR
// Check for control port 2 activity
ldx #$00
stx CIA1_DDRA // set port to input to read joystick
lda CIA1_PRA // read the joystick 2 status
dex // puts $FF
stx CIA1_DDRA // set port back to output
and #%00001111 // filter out anything but joystick movement
cmp #%00001111
bne scnkey_joystick_filtered
#if CONFIG_KEY_FAST_SCAN
inx // puts $00
stx CIA1_PRA // connect all the rows
#if CONFIG_KEYBOARD_C128
stx VIC_XSCAN
#endif
#if CONFIG_KEYBOARD_C65
stx C65_EXTKEYS_PR
#endif
dex // puts $FF
cpx CIA1_PRB
beq scnkey_no_keys
#endif // CONFIG_KEY_FAST_SCAN
#endif // CONFIG_JOY2_CURSOR
// Check for control port 1 activity (can interfere with keyboard)
jsr keyboard_disconnect // disconnect all the rows, .X will be $FF
cpx CIA1_PRB // only control port activity will be reported
#if CONFIG_JOY1_CURSOR
bne scnkey_joystick_1 // use joystick for cursor keys
#else
bne scnkey_no_keys // if activity detected do not scan the keyboard
#endif
// Check if KEYTAB is not 0 (happens if more than one bucky key is pressed)
// High byte equal to 0 = table considered invalid
lda KEYTAB+1
beq scnkey_no_keys
// Scan the keyboard matrix
ldy #$FF // offset in key matrix table, $FF for not found yet
#if CONFIG_KEYBOARD_C128
jsr scnkey_128
#endif
#if CONFIG_KEYBOARD_C65
jsr scnkey_65
#endif
ldx #$07
scnkey_matrix_loop:
lda kb_matrix_row_keys, x
sta CIA1_PRA
lda kb_matrix_bucky_filter, x // filter out bucky keys
ora CIA1_PRB
cmp #$FF
beq scnkey_matrix_loop_next // skip if no key pressed from this row
cpy #$FF
bne scnkey_no_keys // jam, more than one key pressed
// We have at least one key pressed in this row, we need to find which one exactly
ldy #$07
scnkey_matrix_loop_inner:
cmp kb_matrix_row_keys, y
bne !+ // not this particular key
tya // now .A contains key offset within a row
clc
adc kb_matrix_row_offsets, x // now .A contains key offset from the matrix start
tay
jmp scnkey_matrix_loop_next
!:
dey
bpl scnkey_matrix_loop_inner
bmi scnkey_no_keys // branch always, multiple keys must have been pressed
scnkey_matrix_loop_next:
dex
bpl scnkey_matrix_loop
// Scanning complete - check if we got a key
cpy #$FF
beq scnkey_no_keys
// To be extra sure, check for possible control port 1 interference once again
jsr keyboard_disconnect // disconnect all the rows, .X will be $FF
cpx CIA1_PRB // only control port activity will be reported
beq scnkey_got_key // branch if joystick activity NOT detected
// FALLTROUGH
scnkey_no_keys:
// Mark no key press
lda #$40
sta LSTX
rts
#if CONFIG_JOY1_CURSOR
scnkey_joystick_1:
// Prepare joystick 1 status
lda CIA1_PRB
and #%00001111 // filter out anything but movement
// FALLTROUGH
#endif
#if CONFIG_JOY1_CURSOR || CONFIG_JOY2_CURSOR
scnkey_joystick_filtered:
// Set appropriate keyboard matrix and key code for joystick event
ldy #$03
!:
cmp kb_matrix_joy_status, y
beq !+
dey
bpl !-
// Not found
rts
!:
// Found
lda kb_matrix_joy_keytab_lo, y
sta KEYTAB+0
lda kb_matrix_joy_keytab_hi, y
sta KEYTAB+1
lda kb_matrix_joy_keytab_idx, y
tay
// FALLTROUGH
#endif
scnkey_got_key: // .Y should now contain the key offset in matrix pointed by KEYTAB
cpy LSTX
beq scnkey_try_repeat // branch if the same key as previously
sty LSTX
// Reset key repeat counters - see [CM64] page 58
// Note: according to [CM64] it should be $10 for initializing DELAY, $06 for
// initializing KOUNT for the first time and $04 for subsequent ones - but replicating
// this would make our implementation longer, probably without improving the compatibility.
//
// Besides - since I am the one who writes the code, I will make the values exactly how I like them :D
lda #$16
sta DELAY
// FALLTROUGH
scnkey_output_key:
// Check if we have free space in the keyboard buffer
lda NDX
cmp XMAX
bcs scnkey_early_repeat // no space in buffer
// Reinitialize secondary counter
lda #$03
sta KOUNT
// Retrieve the PETSCII code
#if CONFIG_KEYBOARD_C128 || CONFIG_KEYBOARD_C65
cpy #$40
bcc !+
#if CONFIG_KEYBOARD_C128
lda kb_matrix_128 - $41, y // retrieve key code from C128 extended matrix
#elif CONFIG_KEYBOARD_C65
// Select key matrix (normal or shifted) for extended C65 keys
lda SHFLAG
and #%00000111 // KEY_FLAG_SHIFT + KEY_FLAG_VENDOR + KEY_FLAG_CTRL
beq scnkey_output_65_no_shift
cmp #KEY_FLAG_SHIFT
// XXX how to behave on VENDOR/CTRL key? Harmonize this with claasic keys behavior
bne scnkey_no_keys // no scanning for this bucky key combination
lda kb_matrix_65_shifted - $41, y
jmp scnkey_got_petscii
scnkey_output_65_no_shift:
lda kb_matrix_65 - $41, y
#endif
jmp scnkey_got_petscii
!:
lda (KEYTAB), y // retrieve key code from standard matrix
#endif // CONFIG_KEYBOARD_C128 or CONFIG_KEYBOARD_C65
#if CONFIG_KEYBOARD_C128_CAPS_LOCK || CONFIG_KEYBOARD_C65_CAPS_LOCK
// Check if we need special handling for a CAPS LOCK key
// This is shorter than a separate set of tables
scnkey_handle_caps_lock:
#if !CONFIG_KEYBOARD_C128 && !CONFIG_KEYBOARD_C65
lda (KEYTAB), y
#endif
tax
lda SHFLAG
and #(%00000111 + KEY_CAPS_LOCK)
cmp #KEY_CAPS_LOCK
bne !+ // branch if no special CAPS LOCK handling needed
cpx #$41 // 'A'
bcc !+
cpx #$5B // 'Z' + 1
bcs !+
txa
clc
adc #$20 // turn lowercase into uppercase
tax
!:
txa
#endif // CONFIG_KEYBOARD_C128_CAPS_LOCK or CONFIG_KEYBOARD_C65_CAPS_LOCK
#if !CONFIG_KEYBOARD_C128 && !CONFIG_KEYBOARD_C128_CAPS_LOCK && !CONFIG_KEYBOARD_C65 && !CONFIG_KEYBOARD_C65_CAPS_LOCK
lda (KEYTAB), y
#endif
// Output PETSCII code to the keyboard buffer
scnkey_got_petscii:
#if CONFIG_KEYBOARD_C128 && CONFIG_EDIT_TABULATORS
// Special handling for SHIFT+TAB; it is easier than creating new matrix
tax
cmp #KEY_TAB_FW
bne !+
lda SHFLAG
and #KEY_FLAG_SHIFT
beq !+
ldx #KEY_TAB_BW
!:
txa
#endif // CONFIG_KEYBOARD_C128 and CONFIG_EDIT_TABULATORS
beq scnkey_no_keys // branch if we have no PETSCII code for this key
ldy NDX
sta KEYD, y
inc NDX
// FALLTROUGH
scnkey_done:
rts
scnkey_try_repeat:
#if !CONFIG_KEY_REPEAT_ALWAYS
// Check whether we should repeat keys - first the flag, afterwards hardcoded list
lda RPTFLG
bmi scnkey_handle_repeat // branch if we should repeat always
tya
ldx #(__kb_matrix_alwaysrepeat_end - kb_matrix_alwaysrepeat - 1)
!:
cmp kb_matrix_alwaysrepeat, x
beq scnkey_handle_repeat
dex
bpl !-
bmi scnkey_done
scnkey_handle_repeat:
#endif // no CONFIG_KEY_REPEAT_ALWAYS
// Countdown before first repeat
lda DELAY
beq !+
dec DELAY
rts
!:
// Countdown before subsequent repeats
lda KOUNT
beq scnkey_output_key // if second counter is also 0, we can repeat the key
dec KOUNT
rts
scnkey_early_repeat:
// Keyboard buffer was full - at least make sure the key
// will be repeated as soon as possible
lda #$00
sta DELAY
sta KOUNT
rts
via_keylog:
jmp (KEYLOG)
#endif // no CONFIG_LEGACY_SCNKEY