avr: rewrote timer code (split into timer and basetimer).

Only basetimer depends on hardware and clock speed. Works onj AtTiny 84
at 1 MHz and 8 MHz.

avr/modules/basetimer/0BUILD

@@ -0,0 +1,12 @@
+<?xml?>
+
+<gwbuild>
+
+  <extradist>
+    main.asm
+  </extradist>
+
+</gwbuild>
+
+
+

avr/modules/basetimer/main.asm

@@ -0,0 +1,188 @@
+; ***************************************************************************
+; copyright   : (C) 2024 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+;
+; The base timer makes sure that "onSystemTimerTick" is called about every
+; 100ms.
+; The setup depends on hardware and clock.
+;
+
+
+
+; ***************************************************************************
+; data
+
+.dseg
+
+baseTimerModuleData:
+baseTimerModuleReloadValue: .byte 1
+baseTimerModuleTickCounter: .byte 1
+baseTimerTicksSinceLastRun: .byte 2
+baseTimerModuleData_end:
+
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+BASETIMER_BEGIN:
+
+
+
+; ---------------------------------------------------------------------------
+; @rotuine BaseTimer_Init @global
+;
+; @clobbers r16, r17, x
+
+BaseTimer_Init:            ; setup timer for IRQ every 100ms
+  ; reset data in SDRAM
+  ldi xh, HIGH(baseTimerModuleData)
+  ldi xl, LOW(baseTimerModuleData)
+  ldi r16, 0
+  ldi r17, (baseTimerModuleData_end-baseTimerModuleData)
+  rcall Utils_FillSram
+
+  ldi r16, (1<<CS02) | (1<<CS00)  ; Prescaler 1024
+  out TCCR0B, r16
+  
+  ldi r16, (1<<WGM01)             ; CTC mode
+  out TCCR0A, r16
+
+  ldi r16, (1<<OCF0A)             ; clear pending interrupts
+  out TIFR0, r16
+  
+  ldi r16, (1<<OCIE0A)
+  out TIMSK0, r16
+
+;
+; Settings for clock 1Mhz (default)
+; use timer0 with OCR0A=98-1 (irq every 97.65625 millisecs), baseTimerModuleReloadValue 1
+;
+.if clock == 1000000
+  ; CMP-A interrupt about every 100ms
+  ldi r16, 98-1      ; (1,000,000/1024)/10 = 97.65625
+  out OCR0A, r16
+
+  ldi r16, 1
+  sts baseTimerModuleReloadValue, r16
+.endif
+
+;
+; Settings for clock 8Mhz
+; use timer0 with OCR0A=78 (irq every 9.984 millisecs), baseTimerModuleReloadValue 10
+;
+.if clock == 8000000
+  ; CMP-A interrupt about every 10ms
+  ldi r16, 78-1
+  out OCR0A, r16
+
+  ldi r16, 10
+  sts baseTimerModuleReloadValue, r16
+.endif
+
+  sec
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; @routine BaseTimer_Fini @global
+;
+
+BaseTimer_Fini:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine BaseTimer_Run @global
+;
+; @return CFLAG set if something done, cleared otherwise
+; @clobbers all
+
+BaseTimer_Run:
+  push r15
+    in r15, SREG
+    cli
+      lds r24, baseTimerTicksSinceLastRun
+      lds r25, baseTimerTicksSinceLastRun+1
+      clr r16                               ; replace with 0 for next IRQ
+      sts baseTimerTicksSinceLastRun, r16
+      sts baseTimerTicksSinceLastRun+1, r16
+    out SREG, r15                           ; restore global IRQ flag
+  pop r15
+  sbiw r25:r24, 0
+  clc                                     ; flag "nothing done"
+  breq BaseTimer_Run_End
+
+BaseTimer_Run_loop:                       ; for every timer tick
+    push r24
+      push r25
+        rcall onSystemTimerTick
+      pop r25
+    pop r24
+    sbiw r25:r24, 1
+  brne BaseTimer_Run_loop
+  sec
+BaseTimer_Run_End:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine baseTimerIrqOC0A @isr
+;
+; OC0A interrupt handler
+;
+; Increments baseTimerModuleTickCounter, if it reaches 0 then baseTimerTicksSinceLastRun
+; is also incremented and the baseTimerModuleTickCounter reloaded.
+; The rest is done outside ISR baseTimerTicksSinceLastRun in BaseTimer_Run.
+
+baseTimerIrqOC0A:
+  push r15
+    in r15, SREG
+
+    push r24
+      push r25
+        lds r24, baseTimerModuleTickCounter
+        dec r24
+        breq baseTimerIrqOC0A_timerElapsed
+        sts baseTimerModuleTickCounter, r24
+        rjmp baseTimerIrqOC0A_end
+        
+baseTimerIrqOC0A_timerElapsed:
+        lds r24, baseTimerModuleReloadValue  ; reload counter
+        sts baseTimerModuleTickCounter, r24
+        
+        lds r24, baseTimerTicksSinceLastRun
+        lds r25, baseTimerTicksSinceLastRun+1
+        adiw r25:r24, 1
+        sts baseTimerTicksSinceLastRun, r24
+        sts baseTimerTicksSinceLastRun+1, r25
+        
+baseTimerIrqOC0A_end:
+      pop r25
+    pop r24
+    out SREG, r15
+  pop r15
+  reti
+; @end
+
+
+
+BASETIMER_END:
+.equ MODULE_SIZE_BASETIMER = BASETIMER_END-BASETIMER_BEGIN
+
+
+