diff --git a/drivers/Makefile b/drivers/Makefile
index a799114..0d24b7e 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -55,7 +55,8 @@ C64OBJS=\
cbmcharconv.o
C64_OBJS=\
- c64timer.o \
+ clk_timer.o \
+ c64_cps.o \
c64_input.o
A2OBJS=\
@@ -82,11 +83,11 @@ ATROBJS=\
atrcharconv.o
ATR_OBJS=\
- atr_timer.o \
+ clk_timer.o \
atr_input.o
ATRXL_OBJS=\
- atr_timer.xl.o \
+ clk_timer.xl.o \
atr_input.xl.o
VIC20OBJS=\
diff --git a/drivers/atr_timer.s b/drivers/atr_timer.s
deleted file mode 100644
index 40ba3b3..0000000
--- a/drivers/atr_timer.s
+++ /dev/null
@@ -1,141 +0,0 @@
-; timer routines
-;
-; the timer should be a 16-bit counter that's incremented by about
-; 1000 units per second. it doesn't have to be particularly accurate.
-
-.include "atari.inc"
-.include "../inc/common.i"
-
-.export timer_init
-.export timer_read
-.export timer_seconds
-
-.import _atexit
-
-
-.bss
-
-current_time_value: .res 2
-current_seconds: .res 1
-current_jiffies: .res 1
-timer_freq: .res 1 ; VBLANK frequency: 50 - PAL, 60 - NTSC
-timer_freq_reciproc:.res 1 ; reciprocal for timer_freq in ms: 20 - PAL, ~17 - NTSC
-
-.data
-
-vbichain: .word 0
-
-
-.code
-
-; reset timer to 0 and install handler
-; inputs: none
-; outputs: none
-timer_init:
- lda vbichain+1
- bne @done
- lda PAL ; hardware register describing TV system of GTIA
- and #$0e ; mask out irrelevant bits
- bne @ntsc
- ; PAL system
- lda #50
- sta timer_freq
- lda #20
- sta timer_freq_reciproc
- bne @system_set
-@ntsc:
- ; NTSC system
- lda #60
- sta timer_freq
- lda #17
- sta timer_freq_reciproc
-@system_set:
- lda #0 ; initialize time variables
- sta current_time_value
- sta current_time_value+1
- sta current_seconds
- sta current_jiffies
- ldax VVBLKI ; IMMEDIATE VERTICAL BLANK NMI VECTOR
- stax vbichain ; save old immediate vector
- ldy #<timer_vbl_handler
- ldx #>timer_vbl_handler
- lda #6 ; STAGE 1 VBI
- jsr SETVBV ; vector to set VBLANK parameters
-@done:
- ldax #timer_exit
- jmp _atexit
-
-timer_exit:
- lda vbichain+1
- beq @handler_not_installed
- ldy vbichain
- ldx vbichain+1
- lda #6 ; STAGE 1 VBI
- jsr SETVBV ; vector to set VBLANK parameters
- lda #0
- sta vbichain
- sta vbichain+1
-@handler_not_installed:
- rts
-
-; read the current timer value
-; inputs: none
-; outputs: AX = current timer value (roughly equal to number of milliseconds since the last call to 'timer_init')
-timer_read:
- ldax current_time_value
- rts
-
-; tick over the current timer value - should be called 50 or 60 times per second, depending on the TV system
-; inputs: none
-; outputs: none (all registers preserved, but carry flag can be modified)
-timer_vbl_handler:
- pha
- lda timer_freq_reciproc ; ms per tick
- clc
- adc current_time_value
- sta current_time_value
- bcc :+
- inc current_time_value+1
-: inc current_jiffies
- lda current_jiffies
- cmp timer_freq ; full second?
- bne @done ; no, we're done
- lda #0 ; yes, increment "seconds" counter
- sta current_jiffies
- sed
- clc
- lda #$01
- adc current_seconds
- cld
- cmp #$60
- bne :+
- lda #$00
-: sta current_seconds
-@done:
- pla
- jmp SYSVBV ; vector to process immediate VBLANK
-
-timer_seconds:
- lda current_seconds
- rts
-
-
-
-;-- LICENSE FOR atr_timer.s --
-; The contents of this file are subject to the Mozilla Public License
-; Version 1.1 (the "License"); you may not use this file except in
-; compliance with the License. You may obtain a copy of the License at
-; http://www.mozilla.org/MPL/
-;
-; Software distributed under the License is distributed on an "AS IS"
-; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
-; License for the specific language governing rights and limitations
-; under the License.
-;
-; The Original Code is ip65.
-;
-; The Initial Developer of the Original Code is Jonno Downes,
-; jonno@jamtronix.com.
-; Portions created by the Initial Developer are Copyright (C) 2009
-; Jonno Downes. All Rights Reserved.
-; -- LICENSE END --
diff --git a/drivers/c64_cps.s b/drivers/c64_cps.s
new file mode 100644
index 0000000..dbecd6f
--- /dev/null
+++ b/drivers/c64_cps.s
@@ -0,0 +1,13 @@
+; implementation of __clocks_per_sec for C64
+; CC65's C64 runtime library doesn't provide this function
+; this file provides a version in order that clk_timer.s works without 'ifdefs'
+
+.export __clocks_per_sec
+
+.code
+
+__clocks_per_sec:
+ lda #60
+ rts
+
+.end
diff --git a/drivers/clk_timer.s b/drivers/clk_timer.s
new file mode 100644
index 0000000..53a473b
--- /dev/null
+++ b/drivers/clk_timer.s
@@ -0,0 +1,171 @@
+; timer routines
+; this implementation is for Atari and C64.
+; it uses parts of the C runtime library
+;
+; the timer should be a 16-bit counter that's incremented by about
+; 1000 units per second. it doesn't have to be particularly accurate.
+
+.include "../inc/common.i"
+
+.export timer_init
+.export timer_read
+.export timer_seconds
+
+.import __clocks_per_sec, _clock
+.import tosumodeax, tosudiveax
+.import pusheax, incsp4
+.importzp sp, sreg
+
+
+.bss
+
+timer_freq: .res 1 ; VBLANK frequency: 50 - PAL, 60 - NTSC (Atari); always 60 (C64)
+mult_temp: .res 2 ; temp var for multiplication routines
+mult_temp_x:.res 1 ; another temp var for multiplication routines
+
+
+.data
+
+mult: .byte $4C ; JMP opcode
+ .res 2 ; address
+
+
+.code
+
+; get timer frequency and patch multiplication routine pointer
+; inputs: none
+; outputs: none
+timer_init:
+ jsr __clocks_per_sec
+ sta timer_freq
+ cmp #50
+ beq @timer50
+ lda #<mult17
+ ldx #>mult17
+ bne @timerset ; jmp always
+@timer50:
+ lda #<mult20
+ ldx #>mult20
+@timerset:
+ sta mult+1
+ stx mult+2
+ rts
+
+; read the current timer value
+; inputs: none
+; outputs: AX = current timer value in milliseconds
+timer_read = mult
+
+; get current seconds clock hand
+; inputs: none
+; outputs: A = seconds hand (in BCD, range $00..$59)
+timer_seconds:
+ jsr _clock ; return current tick count in sreg:AX (high:low 16bits)
+ jsr pusheax ; push tick count onto stack
+ ldx #0
+ stx sreg
+ stx sreg+1
+ lda timer_freq
+ jsr tosudiveax ; dividend on stack, divisor in sreg:AX
+ jsr pusheax
+ ldx #0
+ stx sreg
+ stx sreg+1
+ lda #60
+ jsr tosumodeax ; result modulo 60
+ ; convert to BCD, a poor man's conversion here....
+ cmp #50
+ bcs @rs_50
+ cmp #40
+ bcs @rs_40
+ cmp #30
+ bcs @rs_30
+ cmp #20
+ bcs @rs_20
+ cmp #10
+ bcs @rs_10
+ rts
+@rs_10:
+ sbc #10
+ ora #$10
+ rts
+@rs_20:
+ sbc #20
+ ora #$20
+ rts
+@rs_30:
+ sbc #30
+ ora #$30
+ rts
+@rs_40:
+ sbc #40
+ ora #$40
+ rts
+@rs_50:
+ sbc #50
+ ora #$50
+ rts
+
+
+; get the current tick count, multiply it by 20, and return the lower 16 bits
+; x*20 = x*16 + x*4
+; inputs: none
+; outputs: AX - tick count times 20 ('milliseconds')
+mult20:
+ jsr _clock ; return current tick count in sreg:AX (high:low 16bits)
+ stx mult_temp_x ; remember high byte of lower 16bits
+ asl a
+ rol mult_temp_x
+ asl a
+ rol mult_temp_x
+ sta mult_temp
+ ldx mult_temp_x
+ stx mult_temp+1 ; mult_temp = ticks * 4
+ asl a
+ rol mult_temp_x
+ asl a
+ rol mult_temp_x ; mult_temp_x:A = 'ticks * 16'
+ clc ; AX - tick count * 16, mult_temp - tick count * 4
+ adc mult_temp
+ sta mult_temp
+ lda mult_temp+1
+ adc mult_temp_x
+ tax
+ lda mult_temp
+ rts
+
+
+; get the current tick count, multiply it by 17, and return the lower 16 bits
+; x*17 = x*16 + x
+; inputs: none
+; outputs: AX - tick count times 17 ('milliseconds')
+mult17:
+ jsr _clock ; return current tick count in sreg:AX (high:low 16bits)
+ sta mult_temp
+ stx mult_temp+1
+ stx mult_temp_x
+ .repeat 4
+ asl a
+ rol mult_temp_x
+ .endrepeat ; mult_temp_x:A = 'ticks * 16'
+ clc
+ adc mult_temp
+ sta mult_temp
+ lda mult_temp+1
+ adc mult_temp_x
+ tax
+ lda mult_temp
+ rts
+
+
+;-- LICENSE FOR clk_timer.s --
+; The contents of this file are subject to the Mozilla Public License
+; Version 1.1 (the "License"); you may not use this file except in
+; compliance with the License. You may obtain a copy of the License at
+; http://www.mozilla.org/MPL/
+;
+; Software distributed under the License is distributed on an "AS IS"
+; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
+; License for the specific language governing rights and limitations
+; under the License.
+; -- LICENSE END --