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Assembly Source File | 1989-12-07 | 16.0 KB | 547 lines

DOSSEG .MODEL SMALL,C COMMENT | MIDIINT.ASM -- Assembler subroutines for MIDIEX patch exchange utility COPYRIGHT (C) 1986 John Bailin, Cantus Corporation Date: 01/02/86 Changed 08/24/86 Jim Bergsten to function using the Microsoft "C" compiler. Summary of changes: 1. PAGE statement added for better output listing. 2. Entry point names prefixed with "_". 3. GROUP, PROG, SEGMENT statements changed to match Microsoft small model standards. 4. Unnecessary stack subtracts and adds removed. 5. Other corrections, simplifications... Changed 11/14/86 by Michael Geary - fixed several bugs Modified 1/22/88 by Dave Hayes - Added support for GMR bulk dumps by increasing size of receive buffer Note: Linkage conventions assume the Microsoft C compiler small model. Modified 12/5/89 by Mike W. Smith: 1. Complete rewrite of code. 2. Fixed interrupt handler to work properly on AT's and 386's. 3. Allows interrupt level and MPU base port to be changed. 4. Allows buffer size to be changed. 5. Changed code to MASM 5.1 simplified directives 6. Other minor corrections | ;------------------------------------------------------------------------------ ; Equates ;------------------------------------------------------------------------------ reset EQU 0FFh ready_to_receive? EQU 01000000b ;Mpu data set ready, active low. data_available? EQU 10000000b ;Mpu data read ready, active low. loop_delay EQU 0FFFFh ;Delay for timeouts. ;------------------------------------------------------------------------------ .DATA extrn buffer_size:word public mpu_data_port,mpu_command_port,mpu_status_port,mpu_irq public irq_mask,eoi,data_in_handler public buffer_ptr,buffer_end,sysex_started,sysex_ended mpu_data_port dw 0330h ;Mpu data port address. mpu_command_port LABEL WORD ;Mpu command port address. mpu_status_port dw 0331h ;Mpu status port address. mpu_irq db 0Ah ;Mpu interrupt level irq_mask db 00000100b ;8259 mask for IRQ 2 eoi dw 0000000001100010b ;End Of Interrupt mask data_in_handler dw no_op ;A NULL routine buffer_ptr dw 0 buffer_end dw 0 sysex_started db 0 ;Sysex receive flags sysex_ended db 0 ; " old_brk_add dw 0,0 .CODE old_int_vect dw 0,0 ;Data must be placed here for proper ; access in the ISR ;______________________________________________________________________________ ; ; MPU interrupt handler ;______________________________________________________________________________ mpu_int proc far push ds ;Save used registers push dx push ax mov ax,DGROUP mov ds,ax ;Set DS to data area mov dx,mpu_status_port ;Test to see if interrupt was initiated in al,dx ; by the MPU. test al,data_available? jz valid_mpu_data ;Yes, goto MPU routines pop ax ;No, restore registers pop dx pop ds jmp dword ptr cs:old_int_vect ;Exit out to old interrupt handler ;Get the data byte from the MPU. valid_mpu_data: sti push cx push bx mov dx,mpu_data_port in al,dx call word ptr data_in_handler ;Changeable data handler ;Acknowledge interrupt mov ax,eoi out 020h,al or ah,ah ;Is an AT being used? jz mi_exit mov al,ah ;Yes, out 0A0h,al ; acknowledge AT's second 8259 mi_exit: pop bx pop cx pop ax pop dx pop ds iret mpu_int endp ;______________________________________________________________________________ ; ; Control Break ISR ;______________________________________________________________________________ break_routine proc far clc ;Signal that dos is to continue ret break_routine endp ;______________________________________________________________________________ ; ; A No Operation routine ;______________________________________________________________________________ no_op proc ret no_op endp ;______________________________________________________________________________ ; ; Queue received mpu data. ; input - al = received data. ;______________________________________________________________________________ receive_sysex proc uses bx cmp al,0F0h ;Is byte SYSEX F0h beginning? jne rs_1 ;No, go on cli mov sysex_started,1 ;Yes, set flag jmp short rs_3 rs_1: cmp sysex_started,1 ;Is a SYSEX currently being inputed? jne rs_exit ;No, exit test al,10000000b ;Is byte end of SYSEX? jz rs_3 ;No, record SYSEX byte ;EOX, set flags and exit rs_2: cli mov sysex_ended,1 mov sysex_started,0 mov al,0F7h ;Force EOX byte ;Store data bytes into buffer rs_3: cli mov bx,buffer_ptr ;Get buffer add bx,buffer_end mov [bx],al ;Store SYSEX byte inc buffer_end ;Increment buffer end mov ax,buffer_end cmp ax,buffer_size ;At the end of the buffer? jb rs_exit ;No, exit ;Buffer overflowed, set last byte to F7h EOX, set flags, and exit mov sysex_ended,1 mov sysex_started,0 mov byte ptr buffer_end[bx],0F7h ;Force EOX byte rs_exit: sti ret receive_sysex endp ;______________________________________________________________________________ ; ; void reset_ctrl_brk(void); ; Resets the Ctrl-Break ISR ;______________________________________________________________________________ reset_ctrl_brk proc uses ds mov dx,old_brk_add mov ds,old_brk_add+2 mov ax,02523h int 021h ret reset_ctrl_brk endp ;______________________________________________________________________________ ; ; void reset_mpu_vector(void); ; Resets the interrupt vector for the MPU-401 ;______________________________________________________________________________ reset_mpu_vector proc uses ds ;Mask off the IRQ line first cmp mpu_irq,06Fh ;Using an AT? ja rmv_1 ;Yes, reset second 8259 cli in al,21h ;Get current mask jmp short $+2 ;Delay for fast processors or al,irq_mask ;Set IRQ mask bit out 21h,al ;Mask IRQ off jmp short rmv_2 rmv_1: cli in al,0A1h ;Read 8259 mask jmp short $+2 ;Delay for fast processors or al,irq_mask ;Set IRQ mask bit out 0A1h,al ;Mask IRQ off rmv_2: sti ;Then restore the old interrupt vector mov ah,25h mov al,mpu_irq mov dx,old_int_vect ;Put old offset into DX mov ds,old_int_vect+2 ;Put old segment into DS int 21h ;Reset the vector ret ;Exit reset_mpu_vector endp ;______________________________________________________________________________ ; ; int second_8259(void); ; Detects a second 8259 ; Returns SUCCESS = 1, FAILURE = 0. ;______________________________________________________________________________ second_8259 proc uses es mov ax,0C000h ;Get system configuration int 015h ;Extended service for AT's mov ax,0 jc s8_exit ;Carry is set, service not supported cmp byte ptr es:[bx+3],0FBh ;XT model? je s8_exit ;Yes, exit cmp byte ptr es:[bx+3],0FEh ;XT model? je s8_exit ;Yes, exit test byte ptr es:[bx+6],040h ;Is bit for 2nd 8259 set? jz s8_exit ;No, no second 8259 mov ax,1 ;Yes, set AX s8_exit: ret second_8259 endp ;______________________________________________________________________________ ; ; int send_command(int command); ; Sends a command to the MPU-401. ; ; returns SUCCESS=-1, FAILURE=0, or command response byte ;______________________________________________________________________________ send_command proc command:byte pushf ;Save flags (interrupt flag) ;Wait for MPU to be ready to receive mov cx,loop_delay ;Timeout loop limit mov dx,mpu_status_port sc_1: in al,dx test al,ready_to_receive? jz sc_2 ;Ready, send byte loop sc_1 ;MPU not ready, exit with error xor ax,ax jmp short sc_10 ;Send command sc_2: cli ;Suspend interrupts mov al,command ;Get command byte out dx,al ;Send it ;Wait for the command acknowledge sc_3: mov cx,loop_delay ;Timeout loop limit mov dx,mpu_status_port sc_4: in al,dx test al,data_available? jz sc_5 ;Data available, go get it loop sc_4 ;Keep trying ;Command ack not returned, exit with error. xor ax,ax jmp short sc_10 ;Get data in sc_5: mov dx,mpu_data_port in al,dx cmp al,0FEh ;Is it an acknowledge? je sc_6 ;Yes, continue call word ptr data_in_handler ;No, have the main data handler handle ; the data byte jmp short sc_3 ;Try again ;Test to see if command sent requires a returned data byte sc_6: mov ax,-1 ;Successful return code cmp command,0A0h ;Less than A0h? jb sc_10 ;Yes, no data byte returned cmp command,0AFh ;More than AFh? ja sc_10 ;Yes, no data byte returned ;Get returning data byte mov cx,loop_delay ;Timeout loop limit mov dx,mpu_status_port sc_7: in al,dx test al,data_available? jz sc_8 ;Data available, go get it loop sc_7 ;Try again ;Command failed to return a data byte, exit with error xor ax,ax jmp short sc_10 ;Get data byte sc_8: mov dx,mpu_data_port in al,dx xor ah,ah ;Exit with return code in AX sc_10: sti ;Restore interrupts popf ;Restore flags ret send_command endp ;______________________________________________________________________________ ; ; int send_data(int databyte); ; Writes data to the MPU. ; ; Returns SUCCESS=1, FAILURE=0. ;______________________________________________________________________________ send_data proc databyte:byte pushf ;Save flags (interrupt flag) ;Wait for MPU to be ready to receive mov cx,loop_delay ;Timeout loop limit mov dx,mpu_status_port sd_1: in al,dx test al,ready_to_receive? jz send_d ;MPU is ready, send data loop sd_1 ;MPU not ready yet, try again ;MPU not ready, exit with error xor ax,ax jmp short sd_exit ;Send the data byte send_d: cli mov al,databyte ;Get data byte mov dx,mpu_data_port out dx,al ;Send it mov ax,1 ;Set AX for no error sd_exit: sti popf ;Restore flags ret send_data endp ;______________________________________________________________________________ ; ; void set_ctrl_brk(void); ; Sets the Ctrl-Break ISR ;______________________________________________________________________________ set_ctrl_brk proc uses es ds mov ax,03523h ;Get original break address int 021h mov old_brk_add,bx mov old_brk_add+2,es mov dx,offset break_routine mov ax,seg break_routine ;Set for new break address mov ds,ax mov ax,02523h int 021h ret set_ctrl_brk endp ;______________________________________________________________________________ ; ; void set_handler(void (*address)(void)); ; Sets the data in handler ;______________________________________________________________________________ set_handler proc address:word cli mov ax,address mov data_in_handler,ax sti ret set_handler endp ;______________________________________________________________________________ ; ; void set_mpu_vector(void); ; Sets the interrupt vector for the MPU-401 ;______________________________________________________________________________ set_mpu_vector proc ;Get current interrupt vector first and save mov ah,035h mov al,mpu_irq ;IRQ level to get int 21h mov cs:old_int_vect,bx ;Save vector offset. mov cs:old_int_vect+2,es ;Save vector segment. ;Set the IRQ vector to the new Interrupt Service Routine push ds ;Save DS mov ah,025h mov al,mpu_irq mov dx,offset mpu_int ;ISR offset mov bx,seg mpu_int mov ds,bx ;ISR segment int 21h ;Set new vector pop ds ;Restore DS ;Unmask the proper IRQ line in the Interrupt controller cmp mpu_irq,06Fh ;Using an AT? ja smv_1 ;Yes, unmask second 8259 cli in al,21h ;Read 8259 mask jmp short $+2 ;Delay for fast processors mov ah,irq_mask ;Get new mask not ah ;Invert for ANDing and al,ah ;Reset IRQ bit out 21h,al ;Enable IRQ jmp short smv_2 smv_1: cli in al,0A1h ;Read second 8259 mask jmp short $+2 ;Delay for fast processors mov ah,irq_mask ;Get new mask not ah ;Invert for ANDing and al,ah ;Reset IRQ bit out 0A1h,al ;Enable IRQ smv_2: sti ret ;Exit set_mpu_vector endp END