Изучаем STM32 на практике. Часть 1. Подключение экрана от Siemens C55

void test_or() {
    PORTB |= 1 << 5;
}

void test_and() {
    PORTB &= ~(1 << 5);
}

void test_xor() {
    PORTB ^= 1 << 5;
}

void test_xor2() {
    PORTB ^= ~(1 << 5);
}

void test_or_arg(uint8_t bit) {
    PORTB |= 1 << bit;
}

00000000 <test_or>:
   0:	2d 9a       	sbi	0x05, 5	; 5
   2:	08 95       	ret

Disassembly of section .text.test_and:

00000000 <test_and>:
   0:	2d 98       	cbi	0x05, 5	; 5
   2:	08 95       	ret

Disassembly of section .text.test_xor:

00000000 <test_xor>:
   0:	85 b1       	in	r24, 0x05	; 5
   2:	90 e2       	ldi	r25, 0x20	; 32
   4:	89 27       	eor	r24, r25
   6:	85 b9       	out	0x05, r24	; 5
   8:	08 95       	ret

Disassembly of section .text.test_xor2:

00000000 <test_xor2>:
   0:	85 b1       	in	r24, 0x05	; 5
   2:	9f ed       	ldi	r25, 0xDF	; 223
   4:	89 27       	eor	r24, r25
   6:	85 b9       	out	0x05, r24	; 5
   8:	08 95       	ret

Disassembly of section .text.test_or_arg:

00000000 <test_or_arg>:
   0:	95 b1       	in	r25, 0x05	; 5
   2:	21 e0       	ldi	r18, 0x01	; 1
   4:	30 e0       	ldi	r19, 0x00	; 0
   6:	08 2e       	mov	r0, r24
   8:	00 c0       	rjmp	.+0      	; 0xa <test_or_arg+0xa>
   a:	22 0f       	add	r18, r18
   c:	0a 94       	dec	r0
   e:	02 f4       	brpl	.+0      	; 0x10 <test_or_arg+0x10>
  10:	92 2b       	or	r25, r18
  12:	95 b9       	out	0x05, r25	; 5
  14:	08 95       	ret