micros checkpoint

Author: nerdralph

src/millis.S

@@ -1,18 +1,15 @@
 ; (c) Ralph Doncaster 2020
 ; ArduinoShrink
 
-; all used io registers are < 0x3F
-;#define __SFR_OFFSET 0
-#include <avr/io.h>
+; #include <avr/io.h>
 
 ;struct {
 ;    uint32_t t0_ovfl;
 ;    uint8_t ovfl_pad;
 ;} t0_millis;
 
-; micros not supported
-.global micros
-micros:
+; ensure timer ISR is brought in by linker
+.global t0_ovfl_inc
 
 .global millis
 millis:
@@ -26,25 +23,3 @@ millis:
     cp r0, r22                          ; has millis changed?
     brne millis
 ret
-
-.global TIMER0_OVF_vect
-TIMER0_OVF_vect:
-    push r16
-    in r16, SREG-0x20
-    push r16
-    push ZL
-    ldi ZL, lo8(t0_millis)
-    push ZH
-    ldi ZH, hi8(t0_millis)
-millis_inc:
-    ld r16, Z
-    subi r16, -1
-    st Z+, r16
-    brcc millis_inc
-    pop ZH
-    pop ZL
-    pop r16
-    out SREG-0x20, r16
-    pop r16
-reti
-