15c7d93ea9
This might sound crazy, but I think it's better to enable the GC by default to avoid surprises. It costs 1130 bytes of flash and 16 bytes of RAM (plus heap overhead) so it's not exactly free, but if needed it can easily be disabled with `-gc=leaking`. On the Uno (32kB flash, 2kB RAM) that's not massive, on the DigiSpark (8kB flash, 0.5kB RAM) that may be too much depending on the application.
71 строка
1,9 КиБ
ArmAsm
71 строка
1,9 КиБ
ArmAsm
; This file provides common code across AVRs that cannot be implemented directly
|
|
; in Go.
|
|
; The reset vector is device-specific and is generated by tools/gen-device-avr.py.
|
|
|
|
; Startup code
|
|
.section .text.__vector_RESET
|
|
.global __vector_RESET
|
|
__vector_RESET:
|
|
clr r1 ; r1 is expected to be 0 by the C calling convention
|
|
|
|
; Set up the stack pointer.
|
|
ldi xl, lo8(_stack_top)
|
|
ldi xh, hi8(_stack_top)
|
|
out 0x3d, xl; SPL
|
|
out 0x3e, xh; SPH
|
|
|
|
; Subtract one from the stack pointer, so it doesn't point in the .data section.
|
|
push r0
|
|
|
|
; Initialize .data
|
|
init_data:
|
|
ldi xl, lo8(_sdata)
|
|
ldi xh, hi8(_sdata)
|
|
ldi yl, lo8(_edata)
|
|
ldi yh, hi8(_edata)
|
|
ldi zl, lo8(_sidata)
|
|
ldi zh, hi8(_sidata)
|
|
init_data_loop:
|
|
cp xl, yl ; if x == y
|
|
cpc xh, yh
|
|
breq init_data_end ; goto main
|
|
lpm r0, Z+ ; r0 = *(z++)
|
|
st X+, r0 ; *(x++) = r0
|
|
rjmp init_data_loop ; goto init_data_loop
|
|
init_data_end:
|
|
|
|
; main will be placed right after here by the linker script so there's no
|
|
; need to jump.
|
|
|
|
|
|
; The only thing this WDT handler really does is disable itself, to get out of
|
|
; sleep mode.
|
|
.section .text.__vector_WDT
|
|
.global __vector_WDT
|
|
__vector_WDT:
|
|
push r16
|
|
|
|
clr r16
|
|
wdr ; Reset watchdog
|
|
out 0x34, r16 ; Clear reset reason (MCUSR)
|
|
|
|
; part 1: set WDCE and WDE to enable editing WDTCSR
|
|
lds r16, 0x60 ; r16 = WDTCSR
|
|
ori r16, 0x18 ; r16 |= WDCE | WDE
|
|
sts 0x60, r16 ; WDTCSR = r16
|
|
|
|
; part 2: within 4 clock cycles, set the new value for WDTCSR
|
|
clr r16
|
|
sts 0x60, r16 ; WDTCSR = 0
|
|
|
|
pop r16
|
|
reti
|
|
|
|
; This is necessary for the garbage collector.
|
|
; It returns the stack pointer as an uintptr.
|
|
.section .text.runtime.getCurrentStackPointer
|
|
.global runtime.getCurrentStackPointer
|
|
runtime.getCurrentStackPointer:
|
|
in r24, 0x3d; SPL
|
|
in r25, 0x3e; SPH
|
|
ret
|