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Assembly Source File | 1991-11-06 | 21.8 KB | 1,084 lines

; ; Data storage for local subroutines ; cmd_ready db SCSI_TESTREADY,0,0,0,0,0 cmd_rewind db SCSI_REWIND,0,0,0,0,0 cmd_sense db SCSI_REQSENSE,0,0,0,size sense,0 cmd_e_sense db SCSI_REQSENSE,0,0,0,size e_sense,0 cmd_format db SCSI_FORMATUNIT,FORMAT_NORMAL,0,0,0,0 cmd_remap db SCSI_REASSIGN,0,0,0,0,0 cmd_space db SCSI_SPACE,1,0,0,0,0 if extended_io cmd_read db SCSI_READBLK,0,0,0,0,0,0,0,1,0 cmd_write db SCSI_WRITEBLK,0,0,0,0,0,0,0,1,0 else cmd_read db SCSI_READBLK,0,0,0,1,0 cmd_write db SCSI_WRITEBLK,0,0,0,1,0 endif cmd_tread db SCSI_READBLK,1,0,0,0,0 cmd_twrite db SCSI_WRITEBLK,1,0,0,0,0 cmd_twritefm db SCSI_WRITEFM,0,0,0,CLOSE_FM_CNT,0 cmd_inquire db SCSI_INQUIRY,0,0,0,size inq,0 cmd_erase db SCSI_ERASE,1,0,0,0,0 cmd_load db SCSI_LOAD,0,0,0,0,0 cmd_capacity db SCSI_READSIZE,0,0,0,0,0,0,0,0,0 cmd_verify db SCSI_VERIFYBLK,0,0,0,0,0,0,0,SECT_TRACK,0 if large_drives even lsect_lsw dw ? lsect_msw dw ? endif even docmd_cmd dw ? docmd_buf dw ? docmd_buf_seg dw ? docmd_len dw ? docmd_ustatus db ? docmd_estatus db ? docmd_message db ? sense_ustatus db ? sense_estatus db ? sense_message db ? retry_cnt db ? if dump_sense sense_msg1 db 0dh,07h,'Unit ' sense_unit db 'xxh, Err ' sense_err db 'xxh, Stat ' sense_ustat db 'xxh, Msg ' sense_msg db 'xxh, Retry ' sense_retry db 'xxh$' sense_msg2 db ', Sense ' sense_code db 'xxh, Addr ' sense_addr3 db 'xx' sense_addr2 db 'xx' sense_addr1 db 'xx' sense_addr0 db 'xxh$' ife monitor sense_msg3 db 0dh,0ah,'$' endif endif ; ; Reset the SCSI Bus ; scsi_reset proc near pusha mov ax,SCSI_CARD_SEG ;Point at the command port mov es,ax mov si,SCSI_CMD_PORT mov byte ptr es:[si],CMDBASE or CMDRST call wait100us mov byte ptr es:[si],CMDBASE call wait100us popa ret scsi_reset endp ; ; Request Sense data from a unit and display the result ; Called after every SCSI command with the exit code in 'al' ; scsi_sense proc near pushf pusha push es if dump_sense ; ; Print out the first part even if we can't retrieve any sense status ; mov al,docmd_estatus ;Save for printing mov sense_estatus,al mov al,docmd_ustatus mov sense_ustatus,al mov al,docmd_message mov sense_message,al mov di,cur_unit mov dl,[di].unit_select lea bx,sense_unit ;Unit call hex2asc2 mov dl,sense_estatus ;Error (from docmd) lea bx,sense_err call hex2asc2 mov dl,sense_ustatus ;Status (from unit) lea bx,sense_ustat call hex2asc2 mov dl,sense_message ;Msg (from unit) lea bx,sense_msg call hex2asc2 mov dl,retry_cnt ;Retry lea bx,sense_retry call hex2asc2 lea dx,sense_msg1 call puts endif ; ; Try to retrieve sense status ; mov di,cur_unit ;Unit lea bx,[di].unit_sense ;Buffer Offset mov cx,size sense ;Buffer Size lea dx,cmd_sense ;Command cmp [di].unit_sense.sense_sense,SENSE_CCS jnz no_e_sense lea bx,[di].unit_e_sense ;Buffer Offset mov cx,size e_sense ;Buffer Size lea dx,cmd_e_sense ;Command no_e_sense: push ds ;Buffer Segment pop es mov di,dx call docmd if dump_sense ; ; If we got something, print it ; jnc sense_dump jmp sense_exit sense_dump: mov di,cur_unit cmp [di].unit_sense.sense_sense,SENSE_CCS jz dump_e_sense mov dl,[di].unit_sense.sense_sense lea bx,sense_code ;Sense call hex2asc2 mov dl,0 lea bx,sense_addr3 call hex2asc2 mov dl,[di].unit_sense.sense_lba_b2 lea bx,sense_addr2 call hex2asc2 mov dl,[di].unit_sense.sense_lba_b1 lea bx,sense_addr1 call hex2asc2 mov dl,[di].unit_sense.sense_lba_b0 lea bx,sense_addr0 call hex2asc2 jmp short sense_print dump_e_sense: mov dl,[di].unit_e_sense.e_sense_sense lea bx,sense_code ;Sense call hex2asc2 mov dl,[di].unit_e_sense.e_sense_lba_b3 lea bx,sense_addr3 ;Address call hex2asc2 mov dl,[di].unit_e_sense.e_sense_lba_b2 lea bx,sense_addr2 call hex2asc2 mov dl,[di].unit_e_sense.e_sense_lba_b1 lea bx,sense_addr1 call hex2asc2 mov dl,[di].unit_e_sense.e_sense_lba_b0 lea bx,sense_addr0 call hex2asc2 sense_print: lea dx,sense_msg2 call puts endif sense_exit: if dump_sense if monitor mov cx,20000 sense_wait: call wait100us loop sense_wait else lea dx,sense_msg3 ;Terminate the Message call puts endif endif pop es popa popf ret scsi_sense endp ; ; Get the Extended Sense Status from the current Unit ; get_sense proc near mov di,cur_unit ;Unit lea bx,[di].unit_e_sense ;Buffer Offset push ds ;Buffer Segment pop es mov cx,size e_sense ;Buffer Size lea di,cmd_e_sense ;Command call docmd ;Always ask first ret get_sense endp ; ; Inquire about the type of a unit ; ; This MUST be the first call to a unit after the reset is done! ; ; al = return code, 'C' error indicates an error ; scsi_inquire proc near push cx ; ; First thing we should do is wait for the unit to be ready ; as it takes some drives a while to spin up. ; mov retry_cnt,READY_RETRY ready_loop1: lea di,cmd_ready ;Command call docmd jnc unit_is_ready cmp al,CNOCONNECT ;No such unit? jz ready_error push cx mov cx,10000 ;Wait 1 Second ready_loop2: call wait100us loop ready_loop2 pop cx dec retry_cnt ;RETRY Times jns ready_loop1 jmp short unit_is_ready ;Still Try the Inquire ready_error: stc jmp short inquire_exit ; ; Then requests its sense status. ; This gives us a chance to find out if the ; device supports the Command Command Set (CCS) ; unit_is_ready: call get_sense jc inquire_exit ; ; Ok, Now find out what kind of device it is ; mov di,cur_unit ;Unit lea bx,[di].unit_inq_buf ;Buffer Offset push ds ;Buffer Segment pop es mov cx,size inq ;Buffer Size lea di,cmd_inquire ;Command call docmd inquire_exit: pop cx ret scsi_inquire endp ; ; Determine the size of a disk ; ; al = return code, 'C' error indicates an error ; scsi_capacity proc near push cx mov retry_cnt,MAX_RETRY capacity_retry: mov di,cur_unit ;Unit lea bx,[di].unit_cap_buf ;Buffer Offset push ds ;Buffer Segment pop es mov cx,size cap ;Buffer Size lea di,cmd_capacity ;Command call docmd jnc capacity_exit call scsi_sense dec retry_cnt jns capacity_retry stc capacity_exit: pop cx ret scsi_capacity endp ; ; Verify (cx) Sectors starting with (dx:ax) ; ; al = return code, 'C' indicates an error ; scsi_verify proc near mov retry_cnt,0 ;Don't do retrys lea di,cmd_verify ;Command mov [di].ver_cmd_lba_b3,dh ;Insert Sector mov [di].ver_cmd_lba_b2,dl ; into Command mov [di].ver_cmd_lba_b1,ah ;Insert Sector mov [di].ver_cmd_lba_b0,al ; into Command mov [di].ver_cmd_len_b1,ch ;Insert Length mov [di].ver_cmd_len_b0,cl ; into Command call docmd jnc verify_exit call scsi_sense verify_exit: ret scsi_verify endp ; ; Read Some Blocks from the disk given ; the request header in es:bx ; ; al = return code, 'C' indicates an error ; disk_read proc near mov retry_cnt,MAX_RETRY mov di,bx mov cx,es:[di].rh4_count ;Sector Count if large_drives mov dx,es:[di].rh4_lsect_lsw ;Starting Sector mov lsect_lsw,dx mov dx,es:[di].rh4_lsect_msw mov lsect_msw,dx else mov dx,es:[di].rh4_sector ;Starting Sector endif mov bx,es:[di].rh4_buf_ofs ;Buffer Offset mov ax,es:[di].rh4_buf_seg ;Buffer Segment mov es,ax mov si,cur_bpb lea di,cmd_read ;Command ife large_drives mov ax,[si].bpb_hs_msw ;Drive Sector Offset if extended_io mov [di].io_cmd_lba_b3,ah ;Insert Sector endif mov [di].io_cmd_lba_b2,al ;Into the Command endif if multi_sector mov ax,cx ;Get Sector Count and ax,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_r_cok1 ;Check for Boundary mov ax,CHUNK_MAX if oldcode disk_r_cok1: shl ax,1 ;Convert to Buffer Size shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 else disk_r_cok1: shl ax,9 ;Convert to Buffer Size endif add ax,bx ;Check for Wrap else mov ax,bx ;Check for Wrap add ax,P_SECT ;The First Time endif disk_r_loop: jnc disk_r_nowrap mov ax,bx ;Normalize the if oldcode shr ax,1 ;Segment and shr ax,1 shr ax,1 shr ax,1 else shr ax,4 ;Segment and endif mov si,es ;Offset so that add si,ax ;It dosn't Wrap mov es,si and bx,000Fh disk_r_nowrap: push cx if large_drives mov dx,lsect_msw if extended_io mov [di].io_cmd_lba_b3,dh mov [di].io_cmd_lba_b2,dl else and dl,01Fh mov [di].io_cmd_lba_b2,dl endif mov dx,lsect_lsw endif mov [di].io_cmd_lba_b1,dh ;Insert Sector mov [di].io_cmd_lba_b0,dl ;Into the Command if multi_sector and cx,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_r_cok2 ;Check for Boundary mov cx,CHUNK_MAX disk_r_cok2: if extended_io mov [di].io_cmd_cnt_b1,ch ;Insert Sector Count endif mov [di].io_cmd_cnt_b0,cl ;Into the Command if oldcode shl cx,1 ;Convert to Buffer Size shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 else shl cx,9 ;Convert to Buffer Size endif else mov cx,P_SECT ;Buffer Size endif disk_r_retry: call docmd jnc disk_r_cok3 call scsi_sense dec retry_cnt jns disk_r_retry ;Already Setup pop cx stc jmp short disk_r_exit if multi_sector disk_r_cok3: pop cx mov ax,cx ;Get Sector Count and ax,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_r_cok4 ;Check for Boundary mov ax,CHUNK_MAX disk_r_cok4: sub cx,ax ;Dec Sector Count jz disk_r_exit if large_drives add lsect_lsw,ax ;Bump to next Sector adc lsect_msw,0 else add dx,ax ;Bump to next Sector endif if oldcode shl ax,1 ;Convert to Buffer Size shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 else shl ax,9 ;Convert to Buffer Size endif add bx,ax jmp disk_r_loop else disk_r_cok3: pop cx if large_drives add lsect_lsw,1 ;Bump to next Sector adc lsect_msw,0 else inc dx ;Bump to next Sector endif add bx,P_SECT loop disk_r_loop clc endif disk_r_exit: mov es,rh_seg mov bx,rh_off pushf mov ax,es:[bx].rh4_count ;Update the Count sub ax,cx mov es:[bx].rh4_count,ax popf ret disk_read endp ; ; Write Some Blocks to the disk given ; the request header in es:bx ; ; al = return code, 'C' indicates an error ; disk_write proc near mov retry_cnt,MAX_RETRY mov di,bx mov cx,es:[di].rh8_count ;Sector Count if large_drives mov dx,es:[di].rh8_lsect_lsw ;Starting Sector mov lsect_lsw,dx mov dx,es:[di].rh8_lsect_msw mov lsect_msw,dx else mov dx,es:[di].rh8_sector ;Starting Sector endif mov bx,es:[di].rh8_buf_ofs ;Buffer Offset mov ax,es:[di].rh8_buf_seg ;Buffer Segment mov es,ax mov si,cur_bpb lea di,cmd_write ;Command ife large_drives mov ax,[si].bpb_hs_msw ;Drive Sector Offset if extended_io mov [di].io_cmd_lba_b3,ah ;Insert Sector endif mov [di].io_cmd_lba_b2,al ;Into the Command endif if multi_sector mov ax,cx ;Get Sector Count and ax,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_w_cok1 ;Check for Boundary mov ax,CHUNK_MAX if oldcode disk_w_cok1: shl ax,1 ;Convert to Buffer Size shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 else disk_w_cok1: shl ax,9 ;Convert to Buffer Size endif add ax,bx ;Check for Wrap else mov ax,bx ;Check for Wrap add ax,P_SECT ;The First Time endif disk_w_loop: jnc disk_w_nowrap mov ax,bx ;Normalize the if oldcode shr ax,1 ;Segment and shr ax,1 shr ax,1 shr ax,1 else shr ax,4 ;Segment and endif mov si,es ;Offset so that add si,ax ;It dosn't Wrap mov es,si and bx,000Fh disk_w_nowrap: push cx if large_drives mov dx,lsect_msw if extended_io mov [di].io_cmd_lba_b3,dh mov [di].io_cmd_lba_b2,dl else and dl,01Fh mov [di].io_cmd_lba_b2,dl endif mov dx,lsect_lsw endif mov [di].io_cmd_lba_b1,dh ;Insert Sector mov [di].io_cmd_lba_b0,dl ;Into the Command if multi_sector and cx,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_w_cok2 ;Check for Boundary mov cx,CHUNK_MAX disk_w_cok2: if extended_io mov [di].io_cmd_cnt_b1,ch ;Insert Sector Count endif mov [di].io_cmd_cnt_b0,cl ;Into the Command if oldcode shl cx,1 ;Convert to Buffer Size shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 shl cx,1 else shl cx,9 ;Convert to Buffer Size endif else mov cx,P_SECT ;Buffer Size endif disk_w_retry: call docmd jnc disk_w_cok3 call scsi_sense dec retry_cnt jns disk_w_retry ;Already Setup pop cx stc jmp short disk_w_exit if multi_sector disk_w_cok3: pop cx mov ax,cx ;Get Sector Count and ax,CHUNK_MAX-1 ;Mask Off the I/O Chunk jnz disk_w_cok4 ;Check for Boundary mov ax,CHUNK_MAX disk_w_cok4: sub cx,ax ;Dec Sector Count jz disk_w_exit if large_drives add lsect_lsw,ax ;Bump to next Sector adc lsect_msw,0 else add dx,ax ;Bump to next Sector endif if oldcode shl ax,1 ;Convert to Buffer Size shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 shl ax,1 else shl ax,9 ;Convert to Buffer Size endif add bx,ax jmp disk_w_loop else disk_w_cok3: pop cx if large_drives add lsect_lsw,1 ;Bump to next Sector adc lsect_msw,0 else inc dx ;Bump to next Sector endif add bx,P_SECT loop disk_w_loop clc endif disk_w_exit: mov es,rh_seg mov bx,rh_off pushf mov ax,es:[bx].rh8_count ;Update the Count sub ax,cx mov es:[bx].rh8_count,ax popf ret disk_write endp ; ; Read Some Blocks from the Tape ; tape_read proc near mov read_flag,TRUE ;Data Read from Tape mov di,bx mov cx,es:[di].rh4_count ;Byte Count mov ax,cx ;Test for invalid and ax,P_SECT-1 ;Byte Count jz tape_r_valid mov error_flag,TRUE mov es:[di].rh4_count,0 ;Nothing Read stc ;Oops ret tape_r_valid: mov bx,es:[di].rh4_buf_ofs ;Buffer Offset mov ax,es:[di].rh4_buf_seg ;Buffer Segment mov es,ax mov ax,bx ;Normalize the if oldcode shr ax,1 ;Segment and shr ax,1 shr ax,1 shr ax,1 else shr ax,4 ;Segment and endif mov si,es ;Offset so that add si,ax ;It dosn't Wrap mov es,si and bx,000Fh lea di,cmd_tread mov ax,cx ;Convert Bytes if oldcode shr ax,1 ;to Blocks shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 else shr ax,9 ;to Blocks endif mov [di].tio_cmd_cnt_b1,ah ;Insert into Command mov [di].tio_cmd_cnt_b0,al call docmd jnc tape_r_ok ; ; Get the Extended Sense Status to check for reading FileMark ; call get_sense ;Get Extended Sense jc tape_r_kaboom mov di,cur_unit ;Unit cmp [di].unit_e_sense.e_sense_sense,80h jnz tape_r_eom tape_r_kaboom: mov error_flag,TRUE ;Real Error Occured stc ret tape_r_eom: mov es,rh_seg mov bx,rh_off mov es:[bx].rh4_count,0 ;Nothing Read clc tape_r_ok: ret tape_read endp ; ; Write Some Blocks to the Tape ; tape_write proc near mov write_flag,TRUE ;Data Written to Tape mov di,bx mov cx,es:[di].rh8_count ;Byte Count mov ax,cx ;Test for invalid and ax,P_SECT-1 ;Byte Count jz tape_w_valid mov es:[di].rh8_count,0 ;Nothing Written mov error_flag,TRUE ;ERROR! stc ;Oops ret tape_w_valid: mov cx,es:[di].rh8_count ;Byte Count mov bx,es:[di].rh8_buf_ofs ;Buffer Offset mov ax,es:[di].rh8_buf_seg ;Buffer Segment mov es,ax mov ax,bx ;Normalize the if oldcode shr ax,1 ;Segment and shr ax,1 shr ax,1 shr ax,1 else shr ax,4 ;Segment and endif mov si,es ;Offset so that add si,ax ;It dosn't Wrap mov es,si and bx,000Fh lea di,cmd_twrite mov ax,cx ;Convert Bytes if oldcode shr ax,1 ;to Blocks shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 shr ax,1 else shr ax,9 ;to Blocks endif mov [di].tio_cmd_cnt_b1,ah ;Insert into Command mov [di].tio_cmd_cnt_b0,al call docmd jnc tape_w_ok ; ; Get the Sense Status and see if we hit EOM. ; This is to allow the FileMark to still be written ; during the close processing. ; call get_sense ;Get Extended Sense jc tape_w_kaboom mov di,cur_unit ;Unit cmp [di].unit_e_sense.e_sense_sense,40h jz tape_w_eom tape_w_kaboom: mov error_flag,TRUE ;Real Error Occured mov es,rh_seg mov bx,rh_off mov es:[bx].rh8_count,0 ;Nothing Written tape_w_eom: stc tape_w_ok: ret tape_write endp ; ; Do a command ; ; bx = buffer offset ; es = buffer segment ; cx = buffer len ; di => command string ; ; al = return code, 'C' indicates an error ; docmd proc near pusha push es mov docmd_buf,bx ;Save our arguments mov docmd_buf_seg,es mov docmd_len,cx mov docmd_cmd,di mov docmd_ustatus,0FFh if monitor mov ax,'F' ;Arbitrate for Bus call show_phase endif mov ax,SCSI_CARD_SEG ;Point at the Card mov es,ax mov si,SCSI_CMD_PORT ;Command Port mov di,SCSI_DATA_PORT ;Data Port mov bx,cur_unit mov al,[bx].unit_select ;Get our Select Bit if reserve_addr ; ; Get us control of the BUS by starting Arbitration ; Wait a maximum of 250ms for Control of the Bus ; or al,080h ;Add our Address mov byte ptr es:[si],CMDBASE nop mov byte ptr es:[di],080h ;Our Address nop mov byte ptr es:[si],CMDBASE or CMDSTARB mov cx,2500 arb_loop: test byte ptr es:[si],STARBCOMPL jnz try_sel call wait100us loop arb_loop else ; ; Wait 250ms for the Bus to become free ; mov cx,2500 idle_loop: test byte ptr es:[si],STBSY ;Busy? jz try_sel call wait100us loop idle_loop endif call scsi_reset mov al,CBUSBUSY ;Bus still BUSY? jmp docmd_exit try_sel: mov byte ptr es:[di],al ;Select Bit nop mov byte ptr es:[si],CMDBASE or CMDENABLE or CMDSEL if monitor mov ax,'S' ;Select Target call show_phase endif ; ; Wait 250 ms for the Target to be SELected ; mov cx,2500 sel_loop: test byte ptr es:[si],STBSY ;Wait for BSY jnz cmd_xfer call wait100us loop sel_loop if monitor mov ax,'A' ;Abort Selection call show_phase endif mov byte ptr es:[si],CMDBASE or CMDSEL call wait100us ;Spec says wait 200us call wait100us ;to abort selection phase test byte ptr es:[si],STBSY ;Look one final time jnz cmd_xfer ;Device did answer mov al,CNOCONNECT ;Nothing Answered jmp docmd_exit ; ; Start the Command, (al) contains last known status ; cmd_xfer: mov byte ptr es:[si],CMDBASE or CMDENABLE nop xfer_loop: mov al,es:[si] ;Get Status Byte test al,STBSY ;Look for BSY bit jnz still_busy jmp xfer_offline if scsi_parity still_busy: test al,STPARERR ;Parity Error? jz still_good jmp xfer_parerr still_good: test al,STREQ ;Request? jz xfer_loop else still_busy: test al,STREQ ;Request? jz xfer_loop endif ; ; Figure out what type of request it is ; and al,REQ_MASK cmp al,REQ_CMDOUT ;Is it Command Out? jnz try_dataout if monitor mov ax,'C' ;Command call show_phase endif mov si,docmd_cmd ;Get Command Pointer movsb ;Send Byte to Card mov docmd_cmd,si mov si,SCSI_CMD_PORT ;Restore Command Port mov di,SCSI_DATA_PORT ;Restore Data Port jmp xfer_loop try_dataout: cmp al,REQ_DATAOUT ;Is it Data Out? jnz try_datain if monitor mov ax,'W' ;Write call show_phase endif mov bx,si mov cx,docmd_len ;Get the Data Count mov si,docmd_buf ;Source Offset mov ds,docmd_buf_seg ;Source Segment cld dataout_loop: test byte ptr es:[bx],STBSY ;Must be BUSY jz dataout_exit test byte ptr es:[bx],STREQ ;Wait for REQ jz dataout_loop movsb ;Transfer a Byte dec di ;Keep in Valid loop dataout_loop ;Done Yet? dataout_exit: mov si,bx ;Restore the Environment mov ax,cs mov ds,ax jmp xfer_loop try_datain: cmp al,REQ_DATAIN ;Is it Data In? jnz try_statin if monitor mov ax,'R' ;Read call show_phase endif mov bx,si mov si,di ;Source Offset mov ax,es mov cx,docmd_len ;Length mov di,docmd_buf ;Dest Offset mov es,docmd_buf_seg ;Dest Segment mov ds,ax ;Source Segment cld datain_loop: test byte ptr [bx],STBSY ;Must be BUSY jz datain_exit test byte ptr [bx],STREQ ;Wait for REQ jz datain_loop movsb ;Transfer a Byte dec si ;Keep in Valid loop datain_loop ;Done Yet? datain_exit: mov ax,ds ;Restore the Environment mov es,ax mov ax,cs mov ds,ax mov di,si mov si,bx jmp xfer_loop try_statin: cmp al,REQ_STATIN ;Is it Status In? jnz try_msgout if monitor mov ax,'s' ;Status call show_phase endif mov al,es:[di] ;Get the Status Byte mov docmd_ustatus,al jmp xfer_loop try_msgout: cmp al,REQ_MSGOUT ;Is it Message Out? jnz try_msgin if monitor mov ax,'M' ;Message Out call show_phase endif mov byte ptr es:[di],MSG_REJECT jmp xfer_loop try_msgin: cmp al,REQ_MSGIN ;Is it Message In? jnz kaboom if monitor mov ax,'m' ;Message In call show_phase endif mov al,es:[di] ;Get the MSG Byte mov docmd_message,al ;And Save it cmp al,MSG_COMPLETE ;Are We All Done? jnz xfer_error cmp docmd_ustatus,0 ;Did we have an error? mov al,COK ;Preload OK code jz docmd_exit jmp xfer_error ;Oops kaboom: call scsi_reset ;Reset the BUS if monitor mov ax,'?' ;Message In call show_phase endif xfer_error: mov al,CERROR ;Command Failed with Bad Status jmp short docmd_exit xfer_offline: mov al,COFFLINE ;Unit went OffLine jmp short docmd_exit xfer_parerr: mov al,CPARERR ;Parity Error Detected jmp short docmd_exit xfer_selerr: mov al,CSELERR ;Re-Select? docmd_exit: mov docmd_estatus,al mov byte ptr es:[si],CMDBASE pop es popa mov al,docmd_estatus cmp al,COK jz docmd_exit_ok stc docmd_exit_ok: ret docmd endp ; ; Wait One Hundred Micros Seconds ; ; The value of 'cx' is computed for an 8 Mhz Clock ; wait100us proc near push cx ; (3) = 375ns mov cx,79 ; (2) = 250ns wait_u_loop: loop wait_u_loop ; (10) = 1250ns * X pop cx ; (5) = 625ns ret ; (11+) = 1375ns wait100us endp ; ; Monitor the Bus Phase on the Video Screen ; if monitor show_phase proc push es push di or ax,VIDEO_COLOR mov di,VIDEO_SEG mov es,di mov di,VIDEO_OFS stosw pop di pop es ret show_phase endp endif