.include "asm_registers.i"
.section .text
.global rcc_config
.global led_config
.global delay_ms
.global led_toggle
.global pseudo_main

.syntax unified
.cpu cortex-m3
.fpu softvfp
.thumb
.align

rcc_config:
    LDR R0, =RCC_BASE
    LDR R1, [R0, #RCC_APB2ENR]
    LDR R2, =(1<<3)
    ORR R1, R1, R2
    STR R1, [R0, #RCC_APB2ENR]
    BX LR

led_config:
    LDR R0, =GPIOB_BASE
    LDR R1, [R0, #GPIO_CRH]
    LDR R2, =~(3<<16)
    AND R1, R1, R2
    LDR R2, =(3<<16)
    ORR R1, R1, R2
    STR R1, [R0, #GPIO_CRH]
    BX LR

delay_ms:
    CMP R0, #0
    BEQ end
    SUBS R0, #1
    MOV.W R1, #1000
loop:
    SUBS R1, #1
    CMP R1, #0
    NOP
    NOP
    NOP
    BNE loop
    B delay_ms
end:
    BX LR

led_toggle:
    LDR R0, =GPIOB_BASE
    LDR R1, [R0, #GPIO_ODR]
    EOR R1, #(1<<12)
    STR R1, [R0, #GPIO_ODR]
    BX LR

pseudo_main:
    BL rcc_config
    BL led_config

while_loop:
    BL led_toggle
    MOV.W R0, #1000
    BL delay_ms
    B while_loop

    BX LR