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ich_wav5.asm
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ich_wav5.asm
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; 19/05/2024
; 19/11/2023
; 18/11/2023
; 17/11/2023
; 16/11/2023
; 15/11/2023
; 14/11/2023
; 13/11/2023
; 03/11/2023 - 11/11/2023
; DOS based .WAV player using AC'97 and codec interface.
; ---------------------------------------------------------------
; NASM version: Erdogan Tan (29/11/2016)
; Last Update: 17/02/2017 (by Erdogan Tan)
; AC97 interrupt version - 09/11/2023 - Erdogan Tan
; sample rate conversion version - 13/11/2023 - Erdogan Tan
; LVI interrupt version (instead of IOC) - 18/11/2023 - Erdogan Tan
; ICHWAV.ASM
; player internal variables and other equates.
BUFFERSIZE equ 64 * 1024 ; 64k file buffer size.
ENDOFFILE equ BIT0 ; flag for knowing end of file
;===========================================================================
; entry: none. File is already open and [filehandle] filled.
; exit: not until the song is finished or the user aborts.
;
playWav:
; 13/11/2023
cmp byte [VRA], 1
jb short chk_sample_rate
playwav_48_khz:
mov word [loadfromwavfile], loadFromFile
;mov word [loadsize], 0 ; 65536
mov word [buffersize], 32768 ; samples
jmp playWav_vra
chk_sample_rate:
; set conversion parameters
; (for 8, 11.025, 16, 22.050, 24, 32 kHZ)
mov ax, [sample_rate]
cmp ax, 48000
je short playwav_48_khz
chk_22khz:
cmp ax, 22050
jne short chk_11khz
cmp byte [bps], 8
jna short chk_22khz_1
mov bx, load_22khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_22khz_2
mov bx, load_22khz_mono_16_bit
jmp short chk_22khz_2
chk_22khz_1:
mov bx, load_22khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_22khz_2
mov bx, load_22khz_mono_8_bit
chk_22khz_2:
mov ax, 7514 ; (442*17)
mov dx, 37
mov cx, 17
jmp set_sizes
chk_11khz:
cmp ax, 11025
jne short chk_44khz
cmp byte [bps], 8
jna short chk_11khz_1
mov bx, load_11khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_11khz_2
mov bx, load_11khz_mono_16_bit
jmp short chk_11khz_2
chk_11khz_1:
mov bx, load_11khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_11khz_2
mov bx, load_11khz_mono_8_bit
chk_11khz_2:
mov ax, 3757 ; (221*17)
mov dx, 74
mov cx, 17
jmp set_sizes
chk_44khz:
cmp ax, 44100
jne short chk_16khz
cmp byte [bps], 8
jna short chk_44khz_1
mov bx, load_44khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_44khz_2
mov bx, load_44khz_mono_16_bit
jmp short chk_44khz_2
chk_44khz_1:
mov bx, load_44khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_44khz_2
mov bx, load_44khz_mono_8_bit
chk_44khz_2:
;mov ax, 15065 ; (655*23)
; 18/11/2023 ((file size + bss + stack) <= 64KB)
mov ax, 14076 ; (612 *23)
mov dx, 25
mov cx, 23
jmp set_sizes
chk_16khz:
cmp ax, 16000
jne short chk_8khz
cmp byte [bps], 8
jna short chk_16khz_1
mov bx, load_16khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_16khz_2
mov bx, load_16khz_mono_16_bit
jmp short chk_16khz_2
chk_16khz_1:
mov bx, load_16khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_16khz_2
mov bx, load_16khz_mono_8_bit
chk_16khz_2:
mov ax, 5461
mov dx, 3
mov cx, 1
jmp set_sizes
chk_8khz:
cmp ax, 8000
jne short chk_24khz
cmp byte [bps], 8
jna short chk_8khz_1
mov bx, load_8khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_8khz_2
mov bx, load_8khz_mono_16_bit
jmp short chk_8khz_2
chk_8khz_1:
mov bx, load_8khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_8khz_2
mov bx, load_8khz_mono_8_bit
chk_8khz_2:
mov ax, 2730
mov dx, 6
mov cx, 1
jmp short set_sizes
chk_24khz:
cmp ax, 24000
jne short chk_32khz
cmp byte [bps], 8
jna short chk_24khz_1
mov bx, load_24khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_24khz_2
mov bx, load_24khz_mono_16_bit
jmp short chk_24khz_2
chk_24khz_1:
mov bx, load_24khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_24khz_2
mov bx, load_24khz_mono_8_bit
chk_24khz_2:
mov ax, 8192
mov dx, 2
mov cx, 1
jmp short set_sizes
chk_32khz:
cmp ax, 32000
jne short vra_needed
cmp byte [bps], 8
jna short chk_32khz_1
mov bx, load_32khz_stereo_16_bit
cmp byte [stmo], 1
jne short chk_32khz_2
mov bx, load_32khz_mono_16_bit
jmp short chk_32khz_2
chk_32khz_1:
mov bx, load_32khz_stereo_8_bit
cmp byte [stmo], 1
jne short chk_32khz_2
mov bx, load_32khz_mono_8_bit
chk_32khz_2:
mov ax, 10922
mov dx, 3
mov cx, 2
;jmp short set_sizes
set_sizes:
cmp byte [stmo], 1
je short ss_1
shl ax, 1
ss_1:
cmp byte [bps], 8
jna short ss_2
; 16 bit samples
shl ax, 1
ss_2:
mov [loadsize], ax
mul dx
;cmp cx, 1
;je short ss_3
;ss_3:
div cx
mov cl, [fbs_shift]
shl ax, cl
shr ax, 1 ; buffer size is 16 bit sample count
mov [buffersize], ax
mov [loadfromwavfile], bx
jmp short playWav_vra
vra_needed:
; 13/11/2023
pop ax ; discard return address to the caller
mov dx, msg_no_vra
jmp vra_err
; 13/11/2023
loadfromwavfile:
dw loadFromFile
loadsize: ; read from wav file
dw 0
buffersize: ; write to DMA buffer
dd 32768 ; 16 bit samples (not bytes)
playWav_vra:
; 07/11/2023
; clear buffer 2
;push es
;mov ax, [WAV_BUFFER2]
;mov es, ax
;sub ax, ax
;mov di, ax ; 17/02/2017
;mov cx, (BUFFERSIZE/2)
;rep stosw
;pop es
; load 64k into buffer 1
mov ax, [WAV_BUFFER1]
;call loadFromFile
; 13/11/2023
call word [loadfromwavfile]
; and 64k into buffer 2
mov ax, [WAV_BUFFER2]
;call loadFromFile
; 13/11/2023
call word [loadfromwavfile]
; register reset the DMA engine. This may cause a pop noise on the output
; lines when the device is reset. Prolly a better idea to mute output, then
; reset.
; 11/11/2023
;mov dx, [NABMBAR]
;add dx, PO_CR_REG ; set pointer to Ctrl reg
;mov al, RR ; set reset
;out dx, al ; self clearing bit
; write last valid index to 31 to start with.
; The Last Valid Index register tells the DMA engine when to stop playing.
;
; As we progress through the song we change the last valid index to always be
; something other than the index we're currently playing.
;
; 08/11/2023
;; 07/11/2023
;mov al, 1
;;mov al, 31
;call setLastValidIndex
; create Buffer Descriptor List
;
; A buffer descriptor list is a list of pointers and control bits that the
; DMA engine uses to know where to get the .wav data and how to play it.
;
; I set it up to use only 2 buffers of .wav data, and whenever 1 buffer is
; playing, I refresh the other one with good data.
;
;
; For the control bits, you can specify that the DMA engine fire an interrupt
; after a buffer has been processed, but I poll the current index register
; to know when it's safe to update the other buffer.
;
; I set the BUP bit, which tells the DMA engine to just play 0's (silence)
; if it ever runs out of data to play. Good for safety.
;
push es
mov ax, [BDL_BUFFER] ; get segment # for BDL
mov es, ax
mov cx, 32 / 2 ; make 32 entries in BDL
xor di, di
_0:
; set buffer descriptor 0 to start of data file in memory
movzx eax, word [WAV_BUFFER1]
shl eax, 4 ; convert seg:off ->0:offset
stosd ; store pointer to wavbuffer1
;
; set length to 32k samples. 1 sample is 16bits or 2bytes.
; Set control (bits 31:16) to BUP, bits 15:0=number of samples.
;
; 17/02/2017 (Erdogan Tan)
; Intel® 82801AA (ICH) & Intel® 82801AB (ICH0) I/O Controller Hub AC’97
; Programmer’s Reference Manual
; 2.2.1 Buffer Descriptor List (on Page 13)
;
; Generic Form of Buffer Descriptor
; ---------------------------------
; 63 62 61-48 47-32 31-0
; --- --- -------- ------- -----
; IOC BUP -reserved- Buffer Buffer
; Length Pointer
; [15:0] [31:0]
;
; IOC: Interrupt On Completion.
; 1 = Enabled.
; When this is set, it means that the controller should
; issue an interrupt upon completion of this buffer.
; It should also set the IOC bit in the status register
; 0 = Disabled
;
; BUP: Buffer Underrun Policy.
; 0 = When this buffer is complete,
; if the next buffer is not yet ready
; (i.e., the last valid buffer has been processed),
; then continue to transmit the last valid sample.
; 1 = When this buffer is complete,
; if this is the last valid buffer, transmit zeros after
; this buffer has been processed completely.
; This bit typically is set only if this is the last
; buffer in the current stream.
;
; [31:0]: Buffer pointer. This field points to the location of
; the data buffer. Since samples can be as wide as one
; word, the buffer must be aligned with word boundaries,
; to prevent samples from straddling DWord boundaries.
;
; [15:0]: Buffer Length: This is the length of the data buffer,
; in number of samples. The controller uses this data
; to determine the length of the buffer, in bytes.
; "0" indicates no sample to process.
; ICH2AC97.INC
; IOC equ BIT31 ; Fire an interrupt whenever this
; buffer is complete.
; BUP equ BIT30 ; Buffer Underrun Policy.
; if this buffer is the last buffer
; in a playback, fill the remaining
; samples with 0 (silence) or not.
; It's a good idea to set this to 1
; for the last buffer in playback,
; otherwise you're likely to get a lot
; of noise at the end of the sound.
;
; Bits 15:0 contain the length of the buffer, in number of samples, which
; are 16 bits each, coupled in left and right pairs, or 32bits each.
; Luckily for us, that's the same format as .wav files.
;
; A value of FFFF is 65536 samples. Running at 44.1Khz, that's just about
; 1.5 seconds of sample time. FFFF * 32bits is 1FFFFh bytes or 128k of data.
;
; A value of 0 in these bits means play no samples.
;
; ICHWAV.ASM
; 19/05/2024
;mov eax, BUFFERSIZE / 2 ; size of buffer (32K) in (16bit) words
; 13/11/2023
mov eax, [buffersize]
; 18/11/2023
; 09/11/2023
;or eax, IOC + BUP
; 06/11/2023
or eax, BUP
stosd
; 2nd buffer:
movzx eax, word [WAV_BUFFER2]
shl eax, 4 ; convert seg:off ->0:offset
stosd ; store pointer to wavbuffer2
; set length to 64k (32k of two 16 bit samples)
; Set control (bits 31:16) to BUP, bits 15:0=number of samples
;
;mov eax, BUFFERSIZE / 2
; 13/11/2023
mov eax, [buffersize]
; 18/11/2023
; 09/11/2023
;or eax, IOC + BUP
; 06/11/2023
or eax, BUP
stosd
loop _0
pop es
;
; tell the DMA engine where to find our list of Buffer Descriptors.
; this 32bit value is a flat mode memory offset (ie no segment:offset)
;
; write NABMBAR+10h with offset of buffer descriptor list
;
movzx eax, word [BDL_BUFFER]
shl eax, 4 ; convert seg:off to 0:off
mov dx, [NABMBAR]
add dx, PO_BDBAR_REG ; set pointer to BDL
out dx, eax ; write to AC97 controller
; 19/05/2024
call delay1_4ms
;
; All set. Let's play some music.
;
; 18/11/2023
; 10/11/2023
; 08/11/2023
; 07/11/2023
; 08/12/2016
; 07/10/2016
mov al, 1 ; 18/11/2023
;mov al, 31
mov [LVI], al ; 10/11/2023
call setLastValidIndex
; 06/11/2023 (not neccessary)
;; 05/11/2023
;; reset current index
;mov al, 0
;call setCurrentIndex
; 06/11/2023
;mov byte [tLoop], 1 ; 30/11/2016
; 19/05/2024
call delay1_4ms
; 17/02/2017
mov dx, [NABMBAR]
add dx, PO_CR_REG ; PCM out Control Register
; 18/11/2023
mov al, LVBIE + RPBM ; Enable LVBI interrupt and run bus master
; 09/11/2023
;mov al, IOCE + RPBM ; Enable 'Interrupt On Completion' + run
; ; (LVBI interrupt will not be enabled)
; 06/11/2023 (TUNELOOP version, without interrupt)
;mov al, RPBM
out dx, al ; Start bus master operation.
; 09/11/2023
mov byte [b_indicator], '?'
; 19/05/2024
; 06/11/2023
call delay1_4ms
call delay1_4ms
call delay1_4ms
call delay1_4ms
; 10/11/2023
;mov byte [tloop], 1
; while DMA engine is running, examine current index and wait until it hits 1
; as soon as it's 1, we need to refresh the data in wavbuffer1 with another
; 64k. Likewise when it's playing buffer 2, refresh buffer 1 and repeat.
; 09/11/2023
; 06/11/2023
%if 1
; 08/12/2016
; 28/11/2016
p_loop:
call check4keyboardstop ; keyboard halt?
jnc short r_loop ; no ; 09/11/2023
; 09/11/2023
;or byte [flags], ENDOFFILE
;mov byte [b_indicator], '0'
q_loop:
;mov al, '0'
call tL0
; 04/11/2023
; finished with song, stop everything
call ac97_stop
; 11/11/2023
irq_restore:
; restore previous interrupt vector and interrupt_status
cli
in al, 0A1h ; irq 8-15
mov al, [IRQ_status+1]
out 0A1h, al
in al, 021h ; irq 0-7
mov al, [IRQ_status]
out 21h, al
; ...
push es
xor ax, ax
mov es, ax
mov ax, [IRQ_vector]
mov [es:bx], ax
mov ax, [IRQ_vector+2]
mov [es:bx+2], ax
pop es
sti
retn
r_loop:
; 19/05/2024
; 10/11/2023
nop
nop
nop
; 11/11/2023
mov al, '0'
cmp byte [tloop], 0
je short p_loop
jl short q_loop
dec byte [tloop] ; 0
cmp byte [b_indicator], '1' ; will be played
jne short s_loop
; 19/11/2023
; load buffer 1
mov ax, [WAV_BUFFER1] ; will be played
u_loop:
;call loadFromFile
; 13/11/2023
call word [loadfromwavfile]
jnc short v_loop
; 19/11/2023
;cmp byte [tloop], -1
;jne short v_loop
mov al, '0'
jmp short q_loop
v_loop:
; 09/11/2023 - Erdogan Tan
; (print buffer number on top left of the screen)
mov al, [b_indicator] ; going to be played
call tL0
jmp short p_loop
s_loop:
; load buffer 2
mov ax, [WAV_BUFFER2] ; will be played
jmp short u_loop
%endif
; while DMA engine is running, examine current index and wait until it hits 1
; as soon as it's 1, we need to refresh the data in wavbuffer1 with another
; 64k. Likewise when it's playing buffer 2, refresh buffer 1 and repeat.
; 18/11/2023
%if 1
tuneLoop:
; 19/11/2023
; 18/11/2023
test byte [flags], ENDOFFILE
jnz short tL3
; 19/11/2023
mov byte [tloop], 1
; set LVI to the next
; (and then load audio data in that buffer)
mov al, [LVI]
inc ax
and al, 1Fh
call setLastValidIndex
;mov [LVI], al
tL1:
; al = next buffer index (not for the buffer being played)
test al, BIT0
jnz short tL2
; 19/11/2023
; load buffer 1
;mov ax, [WAV_BUFFER1] ; will be played
;call word [loadfromwavfile]
;jc short tL3
mov byte [b_indicator], '1'
retn
tL2:
; 19/11/2023
; load buffer 2
;mov ax, [WAV_BUFFER2] ; will be played
;call word [loadfromwavfile]
;jc short tL3
mov byte [b_indicator], '2'
retn
tL3:
mov byte [tloop], -1
stc
retn
; 18/11/2023
tL0:
; al = buffer indicator ('1', '2' or '0' -stop- )
push ds
;push bx
mov bx, 0B800h ; video display page segment
mov ds, bx
sub bx, bx ; 0
mov ah, 4Eh
mov [bx], ax ; show current play buffer (1, 2)
;pop bx
pop ds
retn
%endif
; 11/11/2023
; 10/11/2023
; 09/11/2023
; 08/11/2023
; 07/11/2023
%if 0 ; 18/11/2023
tuneLoop:
; 11/11/2023
; 10/11/2023
; 09/11/2023
; 08/11/2023
; 06/11/2023
;mov al, '1'
;call tL0
tL1:
; 10/11/2023
;mov byte [tloop], 1
; 11/11/2023
;call updateLVI ; set LVI != CIV
;jz short tL4
; 11/11/2023
mov byte [tloop], 1
call getCurrentIndex
; 10/11/2023
cmp al, [LVI]
jne short tL2
test byte [flags], ENDOFFILE
;jnz short tL2
jnz short tL4
dec ax
and al, 1Fh
call setLastValidIndex
xchg al, [LVI]
tL2:
test al, BIT0
jz short tL3
mov byte [b_indicator], '1'
retn
tL3:
mov byte [b_indicator], '2'
retn
tL4:
; 11/11/2023
mov byte [tloop], -1
stc
retn
; 06/11/2023
tL0:
; 08/11/2023
; 05/11/2023
; 17/02/2017 - Buffer switch test (temporary)
; 06/11/2023
; al = buffer indicator ('1', '2' or '0' -stop- )
push ds
;push bx
mov bx, 0B800h ; video display page segment
mov ds, bx
sub bx, bx ; 0
mov ah, 4Eh
mov [bx], ax ; show current play buffer (1, 2)
;pop bx
pop ds
retn
%endif
; 08/11/2023
; 07/11/2023
%if 1
loadFromFile:
; 07/11/2023
test byte [flags], ENDOFFILE ; have we already read the
; last of the file?
jz short lff_0 ; no
stc
retn
lff_0:
; 08/11/2023
mov bp, ax ; save buffer segment
mov cl, [fbs_shift]
and cl, cl
jz short lff_1 ; stereo, 16 bit
mov di, BUFFERSIZE - 1 ; 65535
; fbs_shift =
; 2 for mono and 8 bit sample (multiplier = 4)
; 1 for mono or 8 bit sample (multiplier = 2)
shr di, cl
inc di ; 16384 for 8 bit and mono
; 32768 for 8 bit or mono
mov ax, cs
mov dx, temp_buffer ; temporary buffer for wav data
; 17/02/2017 (stereo/mono, 8bit/16bit corrections)
; load file into memory
mov cx, di
mov bx, [filehandle]
mov ds, ax
mov ah, 3Fh
int 21h
mov bx, cs
mov ds, bx
jc short lff_4 ; error !
; 08/11/2023
xor dx, dx ; 0
and ax, ax
jz short lff_3
mov bl, [fbs_shift]
push es
mov di, dx ; 0 ; [fbs_off]
;mov bp, [fbs_seg] ; buffer segment
mov es, bp
mov si, temp_buffer ; temporary buffer address
mov cx, ax ; byte count
cmp byte [bps], 8 ; bits per sample (8 or 16)
jne short lff_7 ; 16 bit samples
; 8 bit samples
dec bl ; shift count, 1 = stereo, 2 = mono
jz short lff_6 ; 8 bit, stereo
lff_5:
; mono & 8 bit
lodsb
sub al, 80h ; 08/11/2023
shl ax, 8 ; convert 8 bit sample to 16 bit sample
stosw ; left channel
stosw ; right channel
loop lff_5
jmp short lff_9
lff_6:
; stereo & 8 bit
lodsb
sub al, 80h ; 08/11/2023
shl ax, 8 ; convert 8 bit sample to 16 bit sample
stosw
loop lff_6
jmp short lff_9
lff_7:
shr cx, 1 ; word count
lff_8:
lodsw
stosw ; left channel
stosw ; right channel
loop lff_8
lff_9:
pop es
or di, di
jz short endLFF ; 64KB ok
mov ax, di ; [fbs_off]
dec ax
mov cx, BUFFERSIZE - 1 ; 65535
jmp short lff_3
lff_4:
; 08/11/2023
mov al, '!' ; error
call tL0
xor ax, ax
jmp short lff_3
lff_1:
;mov bp, ax ; save buffer segment
xor dx, dx
; load file into memory
mov cx, (BUFFERSIZE / 2) ; 32k chunk
mov bx, [filehandle]
mov ds, ax
mov ah, 3Fh
int 21h
mov di, cs
mov ds, di
; 07/11/2023
jc short lff_4 ; error !
cmp ax, cx
jne short lff_3
lff_2:
; 08/11/2023
add dx, ax
;mov cx, (BUFFERSIZE / 2) ; 32k chunk
;mov bx, [filehandle]
mov ds, bp
mov ah, 3Fh
int 21h
;mov di, cs
mov ds, di
jc short lff_4 ; error !
cmp ax, cx
je short endLFF
lff_3:
call padfill ; blank pad the remainder
;clc ; don't exit with CY yet.
or byte [flags], ENDOFFILE ; end of file flag
endLFF:
retn
%endif
; entry ds:ax points to last byte in file
; cx=target size
; note: must do byte size fill
; destroys bx, cx
;
padfill:
; 07/11/2023
; 06/11/2023
; 17/02/2017
push es
;push di
;mov di, [fbs_seg]
;mov es, di
mov es, bp
sub cx, ax
; 08/11/2023
;mov di, ax ; (wrong)
mov di, dx ; buffer offset
add di, ax
; 07/11/2023
;add di, [fbs_off]
xor al, al
rep stosb
;mov [fbs_off], di
;pop di
pop es
retn
; returns AL = current index value
getCurrentIndex:
; 08/11/2023
;push dx
mov dx, [NABMBAR]
add dx, PO_CIV_REG
in al, dx
;pop dx
uLVI2: ; 06/11/2023
retn
; examines the CIV and the LVI. When they're the same, we set LVI <> CIV
; that way, we never run out of buffers to play
; 08/11/2023
; 07/11/2023
%if 0
updateLVI:
; 06/11/2023
mov dx, [NABMBAR]
add dx, PO_CIV_REG
; (Current Index Value and Last Valid Index value)
in ax, dx
cmp al, ah ; is current index = last index ?
jne short uLVI2
; 10/11/2023
; 08/11/2023
call getCurrentIndex
test byte [flags], ENDOFFILE
;jnz short uLVI1
jz short uLVI0 ; 08/11/2023
; 08/11/2023
push ax
mov dx, [NABMBAR]
add dx, PO_SR_REG ; PCM out status register
in ax, dx
;test al, 2
test al, 3 ; bit 1 = Current Equals Last Valid (CELV)
; (has been processed)
; bit 0 = 1 -> DMA Controller Halted (DCH)
pop ax
jz short uLVI1
uLVI3:
xor ax, ax
; zf = 1
retn
uLVI0:
; not at the end of the file yet.
dec al
and al, 1Fh
uLVI1:
;call setLastValidIndex
;uLVI2:
;retn
%endif
;input AL = index # to stop on
setLastValidIndex:
; 08/11/2023
;push dx
mov dx, [NABMBAR]
add dx, PO_LVI_REG
out dx, al
; 18/11/2023
mov [LVI], al
;pop dx
retn
; checks if either shift key has been pressed. Exits with CY if so.
;
check4keyboardstop:
; 06/11/2023
%if 1
; 19/05/2024
; 08/11/2023
; 04/11/2023
mov ah, 1
int 16h
;clc
jz short _cksr
xor ah, ah
int 16h
;;;
; 19/05/2024 (change PCM out volume)
cmp al, '+'
jne short p_1
mov al, [volume]
cmp al, 0
jna short p_3
dec al
jmp short p_2
p_1:
cmp al, '-'
jne short p_4
mov al, [volume]
cmp al, 31
jnb short p_3
inc al
p_2:
mov [volume], al
mov ah, al
mov dx, [NAMBAR]
;add dx, CODEC_MASTER_VOL_REG
add dx, CODEC_PCM_OUT_REG
out dx, ax