Add support for 4 audio channels, bump version to 0.2.0

audio.asm

@@ -3,96 +3,248 @@
 ; use ffmpeg to convert an audio file for playback:
 ; ffmpeg -i input.mp3 -f s16le -ac 1 -ar 22050 audio.raw
 
-; fox32's audio output works by swapping between two buffers
-; interrupt 0xFE (vector 0x000003F8) is fired when it's time to swap buffers
-; when that interrupt fires, it calls `refill_buffer` which fills up the buffer
-
-const CURRENT_BUFFER: 0x01FFFF00
-const AUDIO_POINTER: 0x01FFFF01
-const AUDIO_LENGTH: 0x01FFFF05
-const OLD_BUFFER_SWAP_VECTOR: 0x01FFFF09
+const AUDIO_POINTER_0:          0x01FFFF00 ; 4 bytes
+const AUDIO_POINTER_1:          0x01FFFF04 ; 4 bytes
+const AUDIO_POINTER_2:          0x01FFFF08 ; 4 bytes
+const AUDIO_POINTER_3:          0x01FFFF0C ; 4 bytes
+const AUDIO_LENGTH_0:           0x01FFFF10 ; 4 bytes
+const AUDIO_LENGTH_1:           0x01FFFF14 ; 4 bytes
+const AUDIO_LENGTH_2:           0x01FFFF18 ; 4 bytes
+const AUDIO_LENGTH_3:           0x01FFFF1C ; 4 bytes
+const OLD_BUFFER_SWAP_VECTOR_0: 0x01FFFF20 ; 4 bytes
+const OLD_BUFFER_SWAP_VECTOR_1: 0x01FFFF24 ; 4 bytes
+const OLD_BUFFER_SWAP_VECTOR_2: 0x01FFFF28 ; 4 bytes
+const OLD_BUFFER_SWAP_VECTOR_3: 0x01FFFF2C ; 4 bytes
 
 ; play an audio clip (does not block)
 ; inputs:
 ; r0: pointer to audio clip
 ; r1: length of audio clip in bytes (must be a multiple of 32768 bytes)
 ; r2: audio sample rate
+; r3: audio channel (0-3)
 ; outputs:
 ; none
 play_audio:
     push r0
     push r1
 
-    ; set the interrupt vector for interrupt 0xFE and save the old one
-    mov [OLD_BUFFER_SWAP_VECTOR], [0x000003F8]
-    mov [0x000003F8], refill_buffer
+    cmp r3, 0
+    ifz jmp play_audio_0
+    cmp r3, 1
+    ifz jmp play_audio_1
+    cmp r3, 2
+    ifz jmp play_audio_2
+    cmp r3, 3
+    ifz jmp play_audio_3
+    jmp play_audio_done
+play_audio_0:
+    ; set the interrupt vector for interrupt 0xFE
+    ; save the old one only if it wasn't already saved earlier
+    cmp [OLD_BUFFER_SWAP_VECTOR_0], refill_buffer_0
+    ifnz mov [OLD_BUFFER_SWAP_VECTOR_0], [0x000003F8]
+    mov [0x000003F8], refill_buffer_0
 
     ; store audio pointer
-    mov [AUDIO_POINTER], r0
+    mov [AUDIO_POINTER_0], r0
 
     ; store audio length
     ; floor it to the nearest multiple of 32768
     and r1, 0xFFFF8000
-    mov [AUDIO_LENGTH], r1
-
-    ; reset the current buffer to zero
-    ; fox32 resets its current buffer to zero internally, so reset it to zero here to stay in sync
-    ; refill_buffer will bitwise not this before checking it,
-    ; so set it to 0xFF so that it becomes zero when checked for the first time
-    mov.8 [CURRENT_BUFFER], 0xFF
+    mov [AUDIO_LENGTH_0], r1
 
     ; enable audio playback and set sample rate
     mov r0, 0x80000600
     out r0, r2
 
+    ; initial buffer fill
+    int 0xFE
+
+    jmp play_audio_done
+play_audio_1:
+    ; set the interrupt vector for interrupt 0xFD
+    ; save the old one only if it wasn't already saved earlier
+    cmp [OLD_BUFFER_SWAP_VECTOR_1], refill_buffer_1
+    ifnz mov [OLD_BUFFER_SWAP_VECTOR_1], [0x000003F4]
+    mov [0x000003F4], refill_buffer_1
+
+    ; store audio pointer
+    mov [AUDIO_POINTER_1], r0
+
+    ; store audio length
+    ; floor it to the nearest multiple of 32768
+    and r1, 0xFFFF8000
+    mov [AUDIO_LENGTH_1], r1
+
+    ; enable audio playback and set sample rate
+    mov r0, 0x80000601
+    out r0, r2
+
+    ; initial buffer fill
+    int 0xFD
+
+    jmp play_audio_done
+play_audio_2:
+    ; set the interrupt vector for interrupt 0xFC
+    ; save the old one only if it wasn't already saved earlier
+    cmp [OLD_BUFFER_SWAP_VECTOR_2], refill_buffer_2
+    ifnz mov [OLD_BUFFER_SWAP_VECTOR_2], [0x000003F0]
+    mov [0x000003F0], refill_buffer_2
+
+    ; store audio pointer
+    mov [AUDIO_POINTER_2], r0
+
+    ; store audio length
+    ; floor it to the nearest multiple of 32768
+    and r1, 0xFFFF8000
+    mov [AUDIO_LENGTH_2], r1
+
+    ; enable audio playback and set sample rate
+    mov r0, 0x80000602
+    out r0, r2
+
+    ; initial buffer fill
+    int 0xFC
+
+    jmp play_audio_done
+play_audio_3:
+    ; set the interrupt vector for interrupt 0xFB
+    ; save the old one only if it wasn't already saved earlier
+    cmp [OLD_BUFFER_SWAP_VECTOR_3], refill_buffer_3
+    ifnz mov [OLD_BUFFER_SWAP_VECTOR_3], [0x000003EC]
+    mov [0x000003EC], refill_buffer_3
+
+    ; store audio pointer
+    mov [AUDIO_POINTER_3], r0
+
+    ; store audio length
+    ; floor it to the nearest multiple of 32768
+    and r1, 0xFFFF8000
+    mov [AUDIO_LENGTH_3], r1
+
+    ; enable audio playback and set sample rate
+    mov r0, 0x80000603
+    out r0, r2
+
+    ; initial buffer fill
+    int 0xFB
+play_audio_done:
     pop r1
     pop r0
     ret
-refill_buffer:
+
+; stop audio playback
+; inputs:
+; r0: audio channel (0-3)
+; outputs:
+; none
+stop_audio:
+    push r0
+
+    ; disable audio playback
+    or r0, 0x80000600
+    out r0, 0
+
+    ; restore the old buffer refill vector
+    cmp.8 r0, 0
+    ifz mov [0x000003F8], [OLD_BUFFER_SWAP_VECTOR_0]
+    cmp.8 r0, 1
+    ifz mov [0x000003F4], [OLD_BUFFER_SWAP_VECTOR_1]
+    cmp.8 r0, 2
+    ifz mov [0x000003F0], [OLD_BUFFER_SWAP_VECTOR_2]
+    cmp.8 r0, 3
+    ifz mov [0x000003EC], [OLD_BUFFER_SWAP_VECTOR_3]
+
+    pop r0
+    ret
+
+refill_buffer_0:
     push r0
     push r1
     push r31
 
-    not.8 [CURRENT_BUFFER]
-    cmp.8 [CURRENT_BUFFER], 0
-    ifnz jmp refill_buffer_1
-refill_buffer_0:
     mov r31, 8192 ; 32768 bytes = 8192 words
-    mov r0, [AUDIO_POINTER]
+    mov r0, [AUDIO_POINTER_0]
     mov r1, 0x0212C000 ; buffer 0 address
-refill_buffer_loop:
+refill_buffer_0_loop:
     mov [r1], [r0]
     add r0, 4
     add r1, 4
-    loop refill_buffer_loop
-    mov [AUDIO_POINTER], r0
-    sub [AUDIO_LENGTH], 32768
+    loop refill_buffer_0_loop
+    mov [AUDIO_POINTER_0], r0
+    sub [AUDIO_LENGTH_0], 32768
+    ifz mov r0, 0
     ifz call stop_audio
 
     pop r31
     pop r1
     pop r0
     reti
+
 refill_buffer_1:
+    push r0
+    push r1
+    push r31
+
     mov r31, 8192 ; 32768 bytes = 8192 words
-    mov r0, [AUDIO_POINTER]
+    mov r0, [AUDIO_POINTER_1]
     mov r1, 0x02134000 ; buffer 1 address
-    jmp refill_buffer_loop
+refill_buffer_1_loop:
+    mov [r1], [r0]
+    add r0, 4
+    add r1, 4
+    loop refill_buffer_1_loop
+    mov [AUDIO_POINTER_1], r0
+    sub [AUDIO_LENGTH_1], 32768
+    ifz mov r0, 1
+    ifz call stop_audio
 
-; stop audio playback
-; inputs:
-; none
-; outputs:
-; none
-stop_audio:
+    pop r31
+    pop r1
+    pop r0
+    reti
+
+refill_buffer_2:
     push r0
+    push r1
+    push r31
 
-    ; disable audio playback
-    mov r0, 0x80000600
-    out r0, 0
+    mov r31, 8192 ; 32768 bytes = 8192 words
+    mov r0, [AUDIO_POINTER_2]
+    mov r1, 0x02290000 ; buffer 2 address
+refill_buffer_2_loop:
+    mov [r1], [r0]
+    add r0, 4
+    add r1, 4
+    loop refill_buffer_2_loop
+    mov [AUDIO_POINTER_2], r0
+    sub [AUDIO_LENGTH_2], 32768
+    ifz mov r0, 2
+    ifz call stop_audio
 
-    ; restore the old buffer swap vector
-    mov [0x000003F8], [OLD_BUFFER_SWAP_VECTOR]
+    pop r31
+    pop r1
+    pop r0
+    reti
 
+refill_buffer_3:
+    push r0
+    push r1
+    push r31
+
+    mov r31, 8192 ; 32768 bytes = 8192 words
+    mov r0, [AUDIO_POINTER_3]
+    mov r1, 0x02298000 ; buffer 3 address
+refill_buffer_3_loop:
+    mov [r1], [r0]
+    add r0, 4
+    add r1, 4
+    loop refill_buffer_3_loop
+    mov [AUDIO_POINTER_3], r0
+    sub [AUDIO_LENGTH_3], 32768
+    ifz mov r0, 3
+    ifz call stop_audio
+
+    pop r31
+    pop r1
     pop r0
-    ret
+    reti

main.asm

@@ -3,7 +3,7 @@
     org 0xF0000000
 
 const FOX32ROM_VERSION_MAJOR: 0
-const FOX32ROM_VERSION_MINOR: 1
+const FOX32ROM_VERSION_MINOR: 2
 const FOX32ROM_VERSION_PATCH: 0
 
 const SYSTEM_STACK:     0x01FFF800