#****************************************************************************************#
#   Project:    task2 - ASM: Interrupts
#   File:       task2.s
#   Hardware:   STefi Light v1.1
#   Processor:  STM32G431KBT6U
#****************************************************************************************#

    .include "G431_addr.s"

    // Falls in G431_addr.s vorhanden, diesen Block löschen um Fehler zu vermeiden:
    .equ RCC_AHB2ENR,    0x4002104C
    .equ RCC_APB2ENR,    0x40021060

    .equ GPIOA_MODER,    0x48000000
    .equ GPIOA_ODR,      0x48000014

    .equ GPIOB_MODER,    0x48000400
    .equ GPIOB_PUPDR,    0x4800040C
    .equ GPIOB_IDR,      0x48000410

    .equ SYSCFG_BASE,    0x40010000
    .equ SYSCFG_EXTICR1, (SYSCFG_BASE + 0x08)
    .equ SYSCFG_EXTICR2, (SYSCFG_BASE + 0x0C)

    .equ EXTI_BASE,      0x40010400
    .equ EXTI_IMR1,      (EXTI_BASE + 0x00)
    .equ EXTI_FTSR1,     (EXTI_BASE + 0x0C)
    .equ EXTI_PR1,       (EXTI_BASE + 0x14)

    .equ NVIC_ISER0,     0xE000E100

    .equ DBGMCU_CR,      0xE0042004  // Adresse des Debug Configuration Registers

#----------------------------------------------------------------------------------------#
    .section .vectortable,"a"
#----------------------------------------------------------------------------------------#

    .align  2

    .word   0x20004000          // initial Stack Pointer
    .word   init                // initial Program Counter
    .word   _ISR_NMI            // non-masking interrupt
    .word   _ISR_HARDF          // hard fault interrupt

    .space  0x48                // Padding 72 Bytes (Offset 0x10 -> 0x58)
    .word   _ISR_EXTI0          // EXTI0_IRQHandler (PB0 / S0) - IRQ 6

    .space  0x0C                // Padding 12 Bytes (Offset 0x5C -> 0x68)
    .word   _ISR_EXTI4          // EXTI4_IRQHandler (PB4 / S1) - IRQ 10

#----------------------------------------------------------------------------------------#
    .text
#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .thumb_func
    .global init
    .type   init, %function
init:
    CPSID   i

    MOVS    r0, #0
    MOVS    r1, #0
    MOVS    r2, #0
    MOVS    r3, #0
    MOVS    r4, #0
    MOVS    r5, #0
    MOVS    r6, #0
    MOVS    r7, #0
    MOV     r8, r0
    MOV     r9, r0
    MOV     r10, r0
    MOV     r11, r0
    MOV     r12, r0

#--- enable port clocking (GPIOA, GPIOB)
    LDR     r1, =RCC_AHB2ENR
    MOVS    r2, #0x03           // Bit 0 (GPIOA) und Bit 1 (GPIOB)
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

#--- port init
#- LEDs (PA0 - PA3) als Output
    LDR     r1, =GPIOA_MODER
    LDR     r2, =0x000000FF
    LDR     r0, [r1, #0]
    BICS    r0, r2
    LDR     r2, =0x00000055
    ORRS    r0, r2
    STR     r0, [r1, #0]

#- switch LED off
    LDR     r1, =GPIOA_ODR
    MOVS    r2, #0x0F
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

#- buttons (PB0, PB4) als Input
    LDR     r1, =GPIOB_MODER
    LDR     r2, =0x00000303     // Maske Bits 0:1 (PB0) und 8:9 (PB4)
    LDR     r0, [r1, #0]
    BICS    r0, r2
    STR     r0, [r1, #0]

#- Pull-Up für PB0, PB4
    LDR     r1, =GPIOB_PUPDR
    LDR     r2, =0x00000303
    LDR     r0, [r1, #0]
    BICS    r0, r2
    LDR     r2, =0x00000101     // 01 = Pull-Up für PB0 und PB4
    ORRS    r0, r2
    STR     r0, [r1, #0]

#--- button interrupt config

#- enable clock for SYSCFG module
    LDR     r1, =RCC_APB2ENR
    MOVS    r2, #0x01
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

#- connect GPIO pins to EXTI lines
    LDR     r1, =SYSCFG_EXTICR1 // EXTI0 (PB0)
    LDR     r2, =0x000F         // Maske EXTI0 (Bits 3:0)
    LDR     r0, [r1, #0]
    BICS    r0, r2
    MOVS    r2, #0x0001         // Port B (0001)
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =SYSCFG_EXTICR2 // EXTI4 (PB4)
    LDR     r2, =0x000F         // Maske EXTI4 (Bits 3:0)
    LDR     r0, [r1, #0]
    BICS    r0, r2
    MOVS    r2, #0x0001         // Port B (0001)
    ORRS    r0, r2
    STR     r0, [r1, #0]

#- configure EXTI lines (falling edge, unmask)
    LDR     r1, =EXTI_FTSR1
    MOVS    r2, #0x11           // Bit 0 (EXTI0) und Bit 4 (EXTI4)
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =EXTI_IMR1
    MOVS    r2, #0x11           // Bit 0 und Bit 4
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

#- NVIC: enable interrupts EXTI0 (IRQ 6) & EXTI4 (IRQ 10)
    LDR     r1, =NVIC_ISER0
    LDR     r2, =0x00000440     // Bit 6 (EXTI0) und Bit 10 (EXTI4)
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

    #--- wachhalten während WFI
    LDR     r1, =DBGMCU_CR
    LDR     r0, [r1, #0]
    MOVS    r2, #0x07           // Setzt DBG_SLEEP, DBG_STOP und DBG_STANDBY Bits
    ORRS    r0, r2
    STR     r0, [r1, #0]

    CPSIE   i

#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .thumb_func
    .global main
    .type   main, %function
main:
    WFI
    B       main

#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .thumb_func
    .global delay
    .type   delay, %function
delay:
    LDR     r0, =106000
.L1:
    SUBS    r0, r0, #1
    BNE     .L1
    BX      lr

#----------------------------------------------------------------------------------------#

    .align 2
    .global stop
stop:
    NOP
    B       stop

#----------------------------------------------------------------------------------------#
.lp1:
    .ltorg
#----------------------------------------------------------------------------------------#

#----------------------------------------------------------------------------------------#
    .section .exhand,"ax"
#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .type   _ISR_NMI, %function
_ISR_NMI:
    LDR     r1, =RCC_AHB2ENR
    MOV     r2, #0x01
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =GPIOA_MODER
    MOVS    r2, #0xFF
    LDR     r0, [r1, #0]
    BICS    r0, r2
    MOVS    r2, #0x44
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =GPIOA_ODR
    MOVS    r2, #0x0A
    LDR     r0, [r1, #0]
    BICS    r0, r2
    STR     r0, [r1, #0]

    B   _ISR_NMI

#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .type   _ISR_HARDF, %function
_ISR_HARDF:
    LDR     r1, =RCC_AHB2ENR
    MOV     r2, #0x01
    LDR     r0, [r1, #0]
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =GPIOA_MODER
    MOVS    r2, #0xFF
    LDR     r0, [r1, #0]
    BICS    r0, r2
    MOVS    r2, #0x11
    ORRS    r0, r2
    STR     r0, [r1, #0]

    LDR     r1, =GPIOA_ODR
    MOVS    r2, #0x05
    LDR     r0, [r1, #0]
    BICS    r0, r2
    STR     r0, [r1, #0]

    B       _ISR_HARDF

#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .type   _ISR_EXTI0, %function
_ISR_EXTI0:
    PUSH    {lr}

#--- Entprellen
    BL      delay

#--- Überprüfen, ob Taster noch gedrückt ist (PB0)
    LDR     r0, =GPIOB_IDR
    LDR     r1, [r0, #0]
    MOVS    r2, #0x01
    TST     r1, r2
    BNE     _clear_exti0

#--- LED0 & LED3 toggeln (1001 = 0x09)
    LDR     r0, =GPIOA_ODR
    LDR     r1, [r0, #0]
    MOVS    r2, #0x09
    EORS    r1, r2
    STR     r1, [r0, #0]

_clear_exti0:
#--- Interrupt Flag löschen
    LDR     r0, =EXTI_PR1
    MOVS    r1, #0x01
    STR     r1, [r0, #0]

    POP     {pc}

#----------------------------------------------------------------------------------------#

    .align  2
    .syntax unified
    .thumb
    .type   _ISR_EXTI4, %function
_ISR_EXTI4:
    PUSH    {lr}

#--- Entprellen
    BL      delay

#--- Überprüfen, ob Taster noch gedrückt ist (PB4)
    LDR     r0, =GPIOB_IDR
    LDR     r1, [r0, #0]
    MOVS    r2, #0x10
    TST     r1, r2
    BNE     _clear_exti4

#--- LED1 & LED2 toggeln (0110 = 0x06)
    LDR     r0, =GPIOA_ODR
    LDR     r1, [r0, #0]
    MOVS    r2, #0x06
    EORS    r1, r2
    STR     r1, [r0, #0]

_clear_exti4:
#--- Interrupt Flag löschen
    LDR     r0, =EXTI_PR1
    MOVS    r1, #0x10
    STR     r1, [r0, #0]

    POP     {pc}

#----------------------------------------------------------------------------------------#
.lp2:
    .ltorg
#----------------------------------------------------------------------------------------#

    .end