.syntax unified
.global main

.type main, %function
main:
  bl init
  b restart

restart:
  mov r0,0        @ Initialize r0 to be played
  mov r4,0        @ Reference register as the current peak

  ldr r6, =array  @ Loading the array location
  ldr r7, [r6, 4] @ Loading the first element on the array
  mov r5, r7      @ Use r5 for reference to compare to r7
  ldr r8, [r6]    @ Size of the array
  mov r9, 1       @ Array Index
  ldr r10, =duration  @ Loading the array location
  ldr r11, [r10, 4] @ Loading the first element on the array
  mov r3, r11      @ Use r5 for reference to compare to r7


  b positive_peak

positive_peak:

  ldr r4, =0x7fff
  mov r0, r4      @ Putting the positive peak value to r0 to be played
  sub r11, 1      @ Checking the duration counter
  cmp r11, 0    @ Comparing it to 12000 to change pitch
  beq change_pitch
  sub r7, 1       @ Adding 1 to the counter
  cmp r7, 0       @ Because the Period = 1/f and the BSP is 48khz then to get the period for 1/440HZ we multiply is by 48khz
                  @ But we need the point for half of a period because each peak is only half a period
                  @ Which is 54.5 but since we can't use float in integer then we use
  beq negative_peak   @This will change the peak to negative peak if high peak has reach the half period
  bl BSP_AUDIO_OUT_Play_Sample

b positive_peak

negative_peak:

  ldr r4, =0x8000
  mov r0, r4
  sub r11, 1
  cmp r11, 0
  beq change_pitch
  add r7, 1      @Substracting 1 to the counter
  cmp r7, r5
                  @ bleq change
                  @when the subs reach 0 then the negative peak has reach half of the period which is 55 then we change it to positive
  beq positive_peak
  bl BSP_AUDIO_OUT_Play_Sample @This will play the sound at the particular value of r0

 b negative_peak


change_pitch:
  add r9, 1      @ Add the Array index
  cmp r8, r9     @ Restart if it has reach the array limit
  beq restart
  mov r12, 4
  mul r12, r9, r12 @ Multiply index with 4 to change the array index by *4 each loop
  ldr r7, [r6,r12]
  mov r5, r7      @ Change the reference pitch to the current pitch
  ldr r11, [r10, r12] @ Loading the first element on the array
  mov r3, r11      @ Use r5 for reference to compare to r7
  b positive_peak

.data
array:
  .word 26        @ Array Size
  @.word 122, 130, 122, 122, 109, 109, 122, 122, 130, 130, 122, 122, 97, 97, 122, 0, 122, 130, 122, 122, 109, 0, 122, 0, 130, 0, 122, 0, 97, 97, 122, 0
  .word 122, 130, 122, 122, 109, 122, 130, 122, 97, 122, 0, 122, 130, 122, 122, 109, 0, 122, 0, 130, 0, 122, 0, 97, 122, 0

duration:
 .word 12000, 12000, 12000, 12000, 24000, 24000, 24000, 24000, 24000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 12000, 24000, 12000, 12000
@196 , 185, 220, 246.94
@122.448  ,  129.729  ,  109.0909  ,  97.189