cleanup some TODOs, #defines

also: hide PORTB2 behind -DDEBUG to save 4 bytes :D

diff --git a/foo.S b/foo.S
index e426ebf..1f7a5c3 100644 (file)
--- a/foo.S
+++ b/foo.S
@@ -1,3 +1,4 @@
+; TODO: melody is still not 100% correct!
 /* REGISTER NAMES */
 #define acc  r16
 #define i0   r17
@@ -11,13 +12,15 @@
 #define _    r25 //==a2
 #define Xlo  r26
 #define Xhi  r27
-;            r28
+#define one  r28
 ;            r29
 ;            r30 Zlo
 ;            r31 Zhi
 ; aliases:
-#define Ml   r23 //mod3 vars
-#define Mh   r24 // -"-
+#define Ml t //mod3 vars
+#define Mh x // -"-
+#define a1 x //mul_ vars
+#define a2 _ // -"-
 
 /* I/O REGISTERS */
 OCR0AL = 0x26
@@ -81,8 +84,6 @@ mod3: ; mod3(Mh.Ml) -> t
        #undef tmp
 
 ; definitions to mul-tree readable:
-#define a1 x
-#define a2 _
 .macro always _bit ; nop; for when a test() is not necessary (see tree)
 .endm
 .macro never _bit  ; nop; for when a test() is not necessary (see tree)
@@ -111,12 +112,8 @@ mod3: ; mod3(Mh.Ml) -> t
 .macro add8 ; ditto with carrying
        ADD     a1, i0
 .endm
-#undef a2
-#undef a1
 
 g: ; g(i, t) -> t
-       #define a1 x
-       #define a2 _
        CLR     a1
 
        #define tmp _
@@ -238,19 +235,16 @@ g: ; g(i, t) -> t
                LSR a1 ;final shift is a common operation for all
 
        MOV     t, a1 ;;TODO: use a1 in loop: directly
-       #undef a1
-       #undef a2
-       RET ; TODO: replace CALL/RET with IJMP?
+       RET
 
 main: ; setup routine
        ; NOTE: clr i0..i2 moved to .ord 0x0
        CLR     i3
        CLR     acc ; we output a dummy sample before the actual first one
        LDI     Xhi, hi8(FLASHM + notes) ; never changes
+       LDI     one, 1      ; mostly for clearing TIM0_OVF bit
 
        #define zero i0
-       #define one _
-       LDI     one, 1
        LDI     x, RAMEND
        OUT     SPL, x      ; init stack ptr
        OUT     SPH, zero   ; -"-
@@ -262,8 +256,7 @@ main: ; setup routine
        OUT     CLKPSR, one ; clock prescaler 1/2 (4Mhz)
        LDI     x, 0xa7     ; determined by trial-and-error (->PORTB2)
        OUT     OSCCAL, x   ; set oscillator calibration
-       OUT     WDTCSR, zero; turn off watchdog ;;TODO: incomplete - see datasheet pg48
-       ; OUT   SMCR, 2     ; sleep mode 'power down' ('idle' (default) has faster response time)
+       OUT     WDTCSR, zero; turn off watchdog
 
        ;set timer/counter0 to 8bit fastpwm, non-inverting, no prescaler
        LDI     x, 0x81
@@ -272,7 +265,6 @@ main: ; setup routine
        OUT     TCCR0B, x
        OUT     TIMSK0, one ; enable tim0_ovf
        SEI
-       #undef one
        #undef zero
 
 loop:
@@ -280,11 +272,10 @@ loop:
        RJMP    loop
 
 sample:
-       ; potential TODO: softcounter in r25 to only update duty cicle every n iterations
-       ; potential TODO: save/restore status register (SREG=0x3f) (only if something in mainloop)
-
        OUT     OCR0AL, acc ; start by outputting a sample, because routine has variable runtime
+#ifdef DEBUG
        SBI     PORTB, 2 ; to measure runtime
+#endif // DEBUG
 
        MOV     n, i2
        LSL     n
@@ -437,7 +428,8 @@ sample:
        SBCI    i2, -1
        SBCI    i3, -1
 
-       CBI     PORTB, 2 ; end runtime measurement
-       LDI     _, 1     ; TODO: could use own register for speed
-       OUT     TIFR0, _ ; clear pending interrupt (routine takes two intr.cycles)
+#ifdef DEBUG
+       CBI     PORTB, 2   ; end runtime measurement
+#endif // DEBUG
+       OUT     TIFR0, one ; clear pending interrupt (routine takes two intr.cycles)
        RETI ; reenables interrupts