js_mdv

**************************
*
*  JS MDV_ROUTINES  mdv_routines
*
***************************

* TRAP 2, D0=3        
L05000 TST.B   $EE(A6)  * Format mdv-Routine: is mdv active ?
       BEQ.S   L0500A   * yes
       MOVEQ   #-9,D0   * "in use"
       RTS

* OPEN CHANNEL FOR FORMATTING       
L0500A MOVE.L  D1,D7    * SAVE VALUE OF D1 AND A1
       MOVEA.L A1,A4
       MOVE.L  #1152,D1   * reserved space
       JSR     L02FAE   * MM.ALCHP
       NOP              * !!! to overvome asm - remove it !!!
       BEQ.S   L0501E   * sucess
       RTS              * error out of mem

*===========
* FORMAT
*===========  
L0501E LEA     $0010(A0),A0   * A0 / A5: BASISADR. FOR FORMATTING
       MOVEA.L A0,A5
       MOVEQ   #-$01,D0
       MOVE.W  D0,(A0)+       * FF followed by placeholder for sector number
       MOVEQ   #$09,D1
L0502A MOVE.B  #$20,(A0)+     * RESERVE 10*SPACE FOR NAME
       DBF     D1,L0502A
       MOVE.W  $002E(A6),(A0) * SV.RND
       SUBA.W  #$000A,A0
       MOVE.W  (A4)+,D1
       ADDQ.W  #5,A4          * skip "MDVn_" prefix
       SUBQ.W  #5,D1
* NOW TRANSFER NAME AND SHORTEN TO MAXIMUM LENGHT 
       CMPI.W  #$000A,D1
       BLS.S   L05048
       MOVEQ   #$0A,D1
L05048 MOVE.B  (A4)+,(A0)+
       SUBQ.W  #1,D1
       BGT.S   L05048
       LEA     $000E(A5),A0
       MOVE.L  #$FD000C10,(A0)+  * FORMAT PARAM.
       ADDQ.W  #6,A0
       MOVE.W  D0,(A0)+
       MOVE.W  #$012A,D1         * LOOP-COUNTER (oversize sector)
L05060 MOVE.W  #$AA55,(A0)+      * EMPTY SECTOR VALUE
       DBF     D1,L05060
       MOVE.W  #$0F0E,$021A(A5)  * EMPTY SECTOR CHECKSUM
       MOVE.W  D7,D1
       LEA     $00018020,A3   * A3 control of ZX8302
       MOVEQ   #$10,D0        * LOOP-COUNTER FOR TRANSMISSION
       JSR     L00420
       NOP                    * !!! to conform asm leave it !!!
       ORI.W   #$0700,SR      * interrupts
       JSR     L02C56         * motor on
       NOP                    * !!! to conform asm leave it !!!
       MOVE.L  #$0001E848,D0  * time 3750600 about 0.5 secs
L0508E SUBQ.L  #1,D0
       BNE.S   L0508E

* main sector format loop
       MOVE.B  #$0A,(A3)      * ERASE mode (erase + read)
L05096 MOVEA.L A5,A1
       MOVEQ   #$0D,D1
       MOVE.W  #$0479,D0      * First GAP duration
L0509E DBF     D0,L0509E
       JSR     L051A6(PC)     * Write sector header
       MOVE.W  #$0261,D1
       MOVE.W  #$047B,D0      * Second GAP duration
L050AE DBF     D0,L050AE
       JSR     L051A6(PC)     * Write sector
       SUBQ.B  #1,-$026F(A1)  * decrease sector number
       BCC.S   L05096         * continue until we've reached sector 0

       MOVE.B  #$02,(A3)      * Switch to READ mode
       CLR.L   -(A7)
       MOVEQ   #$00,D5
L050C4 MOVE.W  #$00FF,D5
L050C8 MOVEA.L A5,A1
       JSR     L0523A(PC)   * read sector header
       BRA.S   L050E6   * error - no synchronisation
       BRA.S   L050E2   * read - error
       JSR     L052A4(PC)  * correct - read more
       BRA.S   L050E2   * error
       ADD.W   D7,D7    * next sector
       SUBQ.B  #1,$00(A1,D7.W)   * adapt sector nr.
       TST.W   D7       * sector 0
       BEQ.S   L050EA   * end verifying
L050E2 DBF     D5,L050C8
L050E6 BRA     L05180   * format failed

L050EA TST.L   D5       * 1. verify
       BLT.S   L050F2   * no
       MOVEQ   #-$01,D5
       BRA.S   L050C4

L050F2 MOVEQ   #$00,D5  * list formatted sectors
L050F4 SUBQ.B  #1,(A1)
       CMPI.B  #$FE,(A1) * IS SECTOR CORRECTLY FORMATTED?
       BGT.S   L05108    * YES BUT NOT SUCCESSFUL
       BEQ.S   L05100    * NO
       ADDQ.W  #1,(A7)   * ADD 1 TO SECTOR-COUNTER
L05100 MOVE.B  D5,$0003(A7) 
       MOVE.B  (A1),D4
       MOVEA.L A1,A4
L05108 ADDQ.W  #2,A1
       ADDQ.B  #1,D5
       BCC.S   L050F4    * CONTINUE TILL CARRY = 255 SECTORS

       ST      (A4)
       ADDQ.B  #2,D4
       BEQ.S   L05116
       SUBQ.W  #1,(A7)
L05116 CMPI.W  #$00C8,(A7) * less than 200 sectors?
       BLT.S   L05180      * error 
       LEA     $000E(A5),A1
       MOVEQ   #$00,D0
L05122 CLR.L   (A1)+
       ADDQ.B  #1,D0
       BPL.S   L05122
       LEA     $0270(A5),A1  * ADRESSE OF SECTOR-LIST
       MOVE.B  #$F8,(A1)
       MOVE.L  (A7),D1
       ADD.W   D1,D1
       SUBI.W  #$0010,D1
L05138 SUBQ.W  #2,D1
       CMPI.B  #$FD,$00(A1,D1.W)
       BNE.S   L05138
       CLR.B   $00(A1,D1.W)
       MOVE.W  D1,$01FE(A1)
       LSR.W   #1,D1
       MOVE.B  D1,(A7)
       MOVEQ   #$00,D2
       JSR     L05222(PC)   * search sector 0
       BRA.S   L05180       * not found - error
       LEA     $0270(A5),A1
       MOVE.W  (A1),-(A7)
       JSR     L051B0(PC)   * write sector catalogue
       ADDQ.W  #2,A7
       MOVE.B  (A7),D2      * last sector in d2
       JSR     L05222(PC)   * read header
       BRA.S   L05180       * failed
       LEA     $000E(A5),A1 * 
       MOVE.L  #$0040,(A1)
       CLR.W   -(A7)
       JSR     L051B0(PC)   * write errors
       ADDQ.W  #2,A7
       MOVEQ   #$00,D7
       BRA.S   L05182       * no errors o.k

L05180 MOVEQ   #-$0E,D7     * format failed
L05182 JSR     L02C50       * stop motor
       NOP                  * !!! to conform asm - leave it out !!!
       LEA     -$0010(A5),A0
       JSR     L0305E
       NOP                  * !!! to conform asm - leave it out !!!
       JSR     L00452
       NOP                  * !!! to conform asm - leave it out !!
       ANDI.W  #$F0FF,SR
       CLR.B   (A7)
       MOVE.W  (A7)+,D1
       MOVE.W  (A7)+,D2
       MOVE.L  D7,D0
       RTS

L051A6 LEA     L051AC(PC),A4  * set continuation address
       BRA.S   L051E4

L051AC MOVEQ   #$0A,D4     * ERASE mode
       BRA.S   L051DA      * Wait, switch to erase and continue

*===========
* MD.WRITE
*===========
L051B0
XL011B0 EQU L051B0-$4000   * write a sector
       MOVE.B  #$0A,(A3)   * ERASE mode (erase + read)
       MOVE.W  #$05C9,D0   * GAP duration
L051B8 DBF     D0,L051B8
       MOVEA.L A1,A0
       LEA     $0004(A7),A1
       MOVEQ   #$01,D1     * 2 bytes (block header)
       LEA     L051CA(PC),A4 * set continuation address
       BRA.S   L051E4      * write block header

L051CA MOVEA.L A0,A1       * data buffer address
       MOVE.W  #$01FF,D1   * 512 bytes (sector data)
       MOVEQ   #$05,D5     * 6 bytes of zero in preamble (3 per track)
       LEA     L051D8(PC),A4 * set continuation address
       BRA.S   L051F2      * write sector data

L051D8 MOVEQ   #$02,D4     * wait and switch to READ mode

L051DA MOVEQ   #$30,D0     * wait for last byte to be completely written
L051DC DBF     D0,L051DC
       MOVE.B  D4,(A3)
       RTS

*
 * common mdv write routine
 *
 * D1 = number of bytes to write
 * A1 = data to write 
 * A3 = mdv control register
 *
L051E4 MOVEQ   #$0E,D0   * WRITE mode (erase + write)
       MOVE.B  D0,(A3)   * A3 = ZX8302 microdrive control
       MOVE.B  D0,(A3)
       MOVEQ   #$01,D6
       LEA     $0002(A3),A2
* write preamble
       MOVEQ   #$09,D5   * 10 x zeros (5 per track)
L051F2 MOVEQ   #$00,D4
L051F4 BSR.S   L0521A
       SUBQ.B  #1,D5
       BGE.S   L051F4
       MOVEQ   #-$01,D4  * 2 x FF (1 per track)
       BSR.S   L0521A
       BSR.S   L0521A
       MOVE.W  #$0F0F,D3 * checksum accumulator
       MOVEQ   #$00,D4
L05206 MOVE.B  (A1)+,D4
       ADD.W   D4,D3     * add to checksum
       BSR.S   L0521A    * write next byte
       DBF     D1,L05206
       MOVE.W  D3,D4
       BSR.S   L0521A    * write checksum
       LSR.W   #8,D4
       BSR.S   L0521A
       JMP     (A4)      * continue execution (probably not RTS to avoid RAM access and keep timing tight)

L0521A BTST    D6,(A3)   * test if ZX8302 busy
       BNE.S   L0521A
       MOVE.B  D4,(A2)
       RTS

L05222 MOVEQ   #$00,D5   * search mdvsector header - d5 counts sectors
L05224 MOVEA.L A5,A1
       BSR.S   L0523A   * do it
       RTS              * failed
       BRA.S   L05224   * read-error
       CMP.B   D7,D2    * was selected sector?
       BEQ.S   L05236
       ADDQ.B  #1,D5
       BCC.S   L05224   * til 255 sectors read
       RTS              * normal return adress

L05236 ADDQ.L  #2,(A7)  * return addr. + 2
       RTS

*===========
* MD.SECTR
*===========
L0523A 
XL0123A EQU L0523A-$4000
* read sector header
       JSR     L05448(PC) * wait for end of gap
       RTS                * failed
       ADDQ.L  #2,(A7)    * correct
       MOVEQ   #$0D,D1
       BSR     L052CE     * read 
       BRA.S   L0525A     * failed
       CMPI.B  #$FF,-$000E(A1) * sector nr. ok
       BNE.S   L0525A
       MOVEQ   #$00,D7
       MOVE.B  -$000D(A1),D7   * return sector nr.
       ADDQ.L  #2,(A7)
L0525A RTS

*===========
* MD.READ
*===========
L0525C 
XL0125C EQU L0525C-$4000
       LEA     L052CE(PC),A0   * read sector (addr. in a0)
       BRA.S   L05266

*===========
* MD.VERIN
*===========
L05262 
XL01262 EQU L05262-$4000
       LEA     L05354(PC),A0   * verify sector addr. in a0

*
* common mdv read
* 
* A0: task-specific routine to read/verify from mdv
* A1: destination buffer
* A3: mdv register
*
L05266 JSR     L05448(PC)      * wait for end of gap and start of data
       RTS                     * failed (timeout)
       MOVE.L  A1,-(A7)
       CLR.W   -(A7)    * allocate two bytes for block header
       MOVEA.L A7,A1
       MOVEQ   #$01,D1
       BSR.S   L052CE   * read block header
       BRA.S   L05296   * failed
       MOVE.B  #$02,D1  * ok
       MOVE.B  D1,(A3)  * set timing (ZX8302)
       MOVEQ   #$08,D0
L05280 DBF     D0,L05280
       MOVE.B  D1,(A3)  * again timing (after 190 cycles from previous, or about 25 us)
       MOVE.W  #$01FF,D1
       MOVEA.L $0002(A7),A1 * a1= buffer address
       JSR     (A0)     * do it
       BRA.S   L05296   * error
       ADDQ.L  #2,$0006(A7)
L05296 MOVEQ   #$00,D1
       MOVEQ   #$00,D2
       MOVE.B  $0001(A7),D2   * block number
       MOVE.B  (A7)+,D1       * file number
       ADDQ.W  #4,A7
       RTS

L052A4 JSR     L05448(PC)   * verify formatted sector / read header
       RTS                  * failed
       MOVE.W  #$0261,D1
       BSR     L05354       * read sector
       RTS                  * failed
       ADDQ.L  #2,(A7)
       RTS

L052B8 MOVE.W  #$0100,D0   * initialise parameters
       MOVE.W  #$0F0F,D3   * d0=counter, d3=checksum
       MOVEQ   #$00,D4
       MOVEQ   #$02,D6
       LEA     $0002(A3),A2   * to read track 1
       LEA     $0003(A3),A4   * to read track 2
       RTS

* read MDV data chunk
L052CE BSR     L052B8     * read number of bits - initialise
L052D0 BTST    D6,(A3)
       DBNE    D0,L052D0  * wait for next byte to be available
       EXG      A4,A4     * !!! WHAT'S THAT ??? !!!
       MOVE.B   (A2),D4   * read track 1 byte
       EXG      A4,A2     * !!! REALLY NECESSARY ?? !!!
       MOVE.B   D4,(A1)+
       ADD.W    D4,D3     * update checksum
       TST.W    D0
       BLT      L05446
       MOVEQ    #$14,D0
       SUBQ.W   #1,D1
L052EA BTST     D6,(A3)   * !!! better: DBNE D0,L052EA (as in JM ROM
       BNE.S      L05338  * but set D0 for better reliability to 28)
L052EE BTST     D6,(A3)   * then omit the following code)!!!
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
       BTST     D6,(A3)
       BNE.S      L05338
o05336 MOVEQ   #-1,D0
L05338 NOP
       NOP              * including this line but: - reset label!
       MOVE.B  (A2),D4  * read track 2 byte
       EXG     A4,A2
       MOVE.B  D4,(A1)+
       ADD.W   D4,D3
       TST.W   D0
       BLT     L05446
       MOVEQ   #$14,D0
       SUBQ.W  #1,D1
       BGE.S   L052EA   * more bytest to read
       BRA     L053DE   * done, go to read checksum

* verify sector data
L05354 BSR     L052B8   * verify reading - initialise
L05358 BTST    D6,(A3)
       DBNE    D0,L05358
       EXG     A4,A4
       MOVE.B  (A2),D4
       EXG     A4,A2
       CMP.B   (A1)+,D4
       BNE     L05446
       ADD.W   D4,D3
       TST.W   D0
       BLT     L05446
       MOVEQ   #$14,D0
       SUBQ.W  #1,D1
L05376 BTST    D6,(A3)   * again wasting ROM space
       BNE.S   L053C4    * !!! replace with dbne d0,L05376 !!!
       BTST    D6,(A3)   * again d0 set to 28
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       BTST    D6,(A3)
       BNE.S   L053C4
       MOVEQ   #-$01,D0
L053C4 NOP
       NOP              * wasting ends here
       MOVE.B  (A2),D4
       EXG     A4,A2
       CMP.B   (A1)+,D4
       BNE.S   L05446
       ADD.W   D4,D3
       TST.W   D0
       BLT     L05446
       MOVEQ   #$14,D0
       SUBQ.W  #1,D1
       BGE.S   L05376
       
* read checksum
L053DE BTST    D6,(A3)  * !!! again as above: dbne d0,L053DE
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       BTST    D6,(A3)
       BNE.S   L0542C
       MOVEQ   #-$01,D0
L0542C NOP
       NOP

L05430 MOVE.B  (A2),D4
       EXG     A4,A2
       ROR.W   #8,D4
       TST.W   D0       * if too long waited
       BLT.S   L05446   * back
       MOVEQ   #$14,D0  * timer
       ADDQ.W  #1,D1
       BEQ.S   L053DE
       CMP.W   D4,D3    * compare checksum
       BNE.S   L05446   * not equal
       ADDQ.L  #2,(A7)  * OK return
L05446 RTS

* wait for end of gap and start of data
L05448 MOVEQ   #$00,D1
L0544A SUBQ.W  #1,D1     * 0.38 seconds
       BEQ.S   L05476    * timeout
       BTST    #$03,(A3) * gap flag from ZX8302
       BEQ.S   L0544A    * if no gap, yet, keep waiting
       MOVEQ   #$00,D1
L05456 SUBQ.W  #1,D1     * wait again 0.38 sec
       BEQ.S   L05476    * timeout
       MOVEQ   #$17,D0   * we'd like to see no gap for at least 24 times
L0545C BTST    #$03,(A3)
       BNE.S   L05456    * gap again, so restart looking
       DBF     D0,L0545C * minimum wait is about 1350 cycles (180 us)
       MOVE.B  #$02,D1
       MOVE.B  D1,(A3)   * set READ mode to skip sector preamble
       MOVEQ   #$08,D0
L0546E DBF     D0,L0546E
       MOVE.B  D1,(A3)
       ADDQ.L  #2,(A7)   * OK return
L05476 RTS

**************************************************
*                                                *
* End MDV_ROUTINES mdv_routines                  *
*                                                *
**************************************************