.syntax unified
.global main, EXTI0_IRQHandler, EXTI1_IRQHandler

.include "macros.s"

main:
  bl init_gpio
  bl init_audio
  bl FourFortySender

@ we will use r11 to keep track of control

set_counter:
  mov r7, #31 @sender_counter
  bx lr

FourFortySender:
  bl set_counter
  @ good luck!
  @lsl r6, #1
  ldr r6, =message
  ldr r9, =#FourFortyHz
  GPIOx_ODR_set E, 12
  bl sender

sender:
  ldr r8, [r9]
  lsr r8, r7  @ bit loaded
  ands r8, #1 @ get the most significant bit
  it ne
  blne sendOne
  it eq  @ send
  bleq sendZero
  GPIOx_ODR_toggle E, 13
  @ orr r6, r8
  cmp r7, #-1
  it eq
  bleq loop
  it ne
  blne sender


sendOne:
  GPIOx_ODR_set E, 14
  bx lr

sendZero:
  GPIOx_ODR_clear E, 14
  bx lr


thinker:
  @ good luck!
  @lsl r6, #1
  ldr r8, [r9]
  lsr r8, r7  @ bit loaded, send
  lsl r8, #31
  lsr r8, #31
  @ orr r6, r8
  cmp r7, #-1
  it eq
  bleq loop
  it ne
  blne receiveOne

loop:
  GPIOx_ODR_clear E, 12
  ldr r6, =message
  ldr r5, [r6]
  nop
  b loop

.type EXTI0_IRQHandler, %function
EXTI0_IRQHandler:
  push {lr}
  EXTI_PR_clear_pending 0
  GPIOx_IDR_read H, 0
  it eq
  moveq r11, #0
  it ne
  movne r11, #1
  pop {lr}
  bx lr

.type EXTI1_IRQHandler, %function
EXTI1_IRQHandler:
  push {lr}
  EXTI_PR_set_pending 0
  cmp r7, #0
  it ne
  blne checker
  pop {lr}
  bx lr

checker:
  GPIOx_IDR_read E, 11
  bne receiveOne
  beq receiveZero

receiveOne:
  ldr r6, =message
  ldr r5, [r6]
  lsl r5, #1
  orr r5, #1
  str r5, [r6]
@  lsl r6, #1
@  orr r6, #1
@  sub r7, #1
  bx lr

receiveZero:
  ldr r6, =message
  ldr r5, [r6]
  lsl r5, #1
  str r5, [r6]
@  lsl r6, #1
@  orr r6, 0b00000000000000000000000000000000
  sub r7, #1
  bx lr

message:
    .word 0
delay:
  .word 0b00000000000000000111111111111111   @ 0Hz in binary (for the delay)
ThreeNinetyTwoHz:                                       @ the least significant 16 bits of each of these are the amplitude 0x7FFF
  .word 0b00000001100010000111111111111111   @ 392Hz in binary
FourNinetyFourHz:
  .word 0b00000001111011100111111111111111   @ 494Hz in binary
FiveTwentyThreeHz:
  .word 0b00000010000010110111111111111111   @ 523Hz in binary
FourFortyHz:
  .word 0b00000001101110000111111111111111   @ 440Hz in binary