29 917
modifications
Modifications
Sauter à la navigation
Sauter à la recherche
Ligne 37 :
Ligne 37 : + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
MicroPython-Hack-assembleur (voir la source)
Version du 19 avril 2015 à 08:50
, 19 avril 2015 à 08:50→Accéder aux périphériques
* {{fname|strh}} stores a half-word (16 bits). The instruction above stores the lower 16-bits of {{fname|r1}} into the memory location {{fname|r0 + stm.GPIO_BSRRL}}. This has the effect of setting high all those pins on port A for which the corresponding bit in {{fname|r0}} is set. In our example above, the 13th bit in {{fname|r0}} is set, so PA13 is pulled high. This turns on the red LED.
* {{fname|strh}} stores a half-word (16 bits). The instruction above stores the lower 16-bits of {{fname|r1}} into the memory location {{fname|r0 + stm.GPIO_BSRRL}}. This has the effect of setting high all those pins on port A for which the corresponding bit in {{fname|r0}} is set. In our example above, the 13th bit in {{fname|r0}} is set, so PA13 is pulled high. This turns on the red LED.
== Accepter des arguments ==
Inline assembler functions can accept up to 3 arguments. If they are used, they must be named {{fname|r0}}, {{fname|r1}} et {{fname|r2}} to reflect the registers and the calling conventions.
Here is a function that adds its arguments:
<nowiki>@micropython.asm_thumb
def asm_add(r0, r1):
add(r0, r0, r1)</nowiki>
This performs the computation {{fname|r0 = r0 + r1}}. Since the result is put in {{fname|r0}}, that is what is returned. Try {{fname|asm_add(1, 2)}}, it should return 3.
== Les boucles ==
We can assign labels with {{fname|label(my_label)}}, and branch to them using {{fname|b(my_label)}}, or a conditional branch like {{fname|bgt(my_label)}}.
The following example flashes the green LED. It flashes it {{fname|r0}} times.
<nowiki>@micropython.asm_thumb
def flash_led(r0):
# get the GPIOA address in r1
movwt(r1, stm.GPIOA)
# get the bit mask for PA14 (the pin LED #2 is on)
movw(r2, 1 << 14)
b(loop_entry)
label(loop1)
# turn LED on
strh(r2, [r1, stm.GPIO_BSRRL])
# delay for a bit
movwt(r4, 5599900)
label(delay_on)
sub(r4, r4, 1)
cmp(r4, 0)
bgt(delay_on)
# turn LED off
strh(r2, [r1, stm.GPIO_BSRRH])
# delay for a bit
movwt(r4, 5599900)
label(delay_off)
sub(r4, r4, 1)
cmp(r4, 0)
bgt(delay_off)
# loop r0 times
sub(r0, r0, 1)
label(loop_entry)
cmp(r0, 0)
bgt(loop1)</nowiki>
{{MicroPython-Hack-ASM-TRAILER}}
{{MicroPython-Hack-ASM-TRAILER}}