hdalloc

;*************************************
;
;  THESE ROUTINES WILL ALLOCATE THE FIRST
;  OR NEXT ALLOCATION
;
;*************************************
;
;  PRIMARY ALLOCATION
;  THIS ROUTINE IS CALLED TO ALLOCATE THE FIRST
;  SECTOR TO A FILE OR TO ALLOCATE
;  A SECTOR TO THE DIRECTORY
;
INTTS
NXTDS
	LDA #1
	LDX #0          ;BEGINNING ZONE
	STA NAHEAD      ;EVERY OTHER SECTOR
	STX TRACK       ;LAST ONE AT T&S 00
	STX SECTOR      ;*
	BEQ HDGS1       ;JMP TO COMMON CODE
;
;  SECONDARY ALLOCATION
;  THIS ROUTINE IS CALLED TO ALLOCATE N SECTORS
;  TO AN EXISTING FILE OR IN THE CASE
;  THAT THE PRIMARY ALLOCATION ZONE
;  IS FULL AN ATTEMPT WILL BE MADE TO ALLOCATE
;  A SECTOR FROM THIS THE NON-PRIME ZONES
;
NXTTS
	LDX #10         ;N AHEAD = 10
	STX NAHEAD      ;*
	LDX #1          ;BEGINNING ZONE NUMBER
;
;  THE FOLLOWING CODE IS COMMON TO BOTH
;
HDGS1
	STX HDTYP       ;SAVE BEG ZONE = REQ TYPE
	STX HDCZN       ;SAVE AS CURRENT ZONE ALSO
	LDX DRVNUM      ;CHK IF VER FLAG SET
	LDA HDDFLG,X    ;*
	AND #HDVIP      ;*
	BEQ HDGS6       ;BR IF
	LDA #VERLK      ;GIVE THE VALIDATE LOCK ERROR
	JSR CMDERR      ;*
HDGS6
;****************************************
;
;  DO OPTIMUM ALLOCATION OF THE SECTOR
;
;****************************************
	LDA TRACK       ;CURRENT TRACK #
	JSR HDGNSB      ;GET # SECTORS THIS TRACK
	STA HDTMPA      ;SAVE
	STA HDTMPB      ;*
	LDA SECTOR      ;CURRENT SECTOR
	AND #$3F        ;TURN OFF HEAD BITS
	CLC             ;ADD THE NUMBER AHEAD
	ADC NAHEAD      ;*
	CMP HDTMPA      ;CHK FOR WRAP
	BCC GS1         ;BR IF NO WRAP AROUND
	SEC             ;CALC # WRAPPED
	SBC HDTMPA      ;*
GS1
	STA HDTMPA      ;SAVE DESIRED SECTOR #
	LDA SECTOR      ;COPY PROPER HEAD BITS
	AND #$C0        ;*
	ORA HDTMPA      ;*
	STA SECTOR      ;*
;CALC # SECTORS TO SEARCH
;BETWEEN HERE AND END OF TRACK
	AND #$3F        ;SECTOR # ONLY
	STA HDTMPA      ;*
	SEC             ;SUBTRACT FROM TOTAL ON TRK
	LDA HDTMPB
	SBC HDTMPA
	STA HDTMPA      ;# TO END OF TRACK
	JSR SRCHET      ;SEARCH TO END OF TRACK
	BEQ GS2         ;BR IF NOT FOUND
GSGOT
	RTS             ;EXIT (NZ=GOT ONE)
GS2
	LDA HDTMPB      ;SEARCH WHOLE TRK
	STA HDTMPA      ;*
	LDA SECTOR      ;*
	AND #$C0        ;BEG AT SECTOR 00
	STA SECTOR      ;*
	JSR SRCHET      ;LOOK FOR ONE
	BNE GSGOT       ;BR IF FOUND ONE
;
;  COULD NOT FIND A SECTOR SO
;  GO BACK TO BEGINNING OF PROPER
;  ZONE AND LOOK TILL END OF DISK
;  FOR A SECTOR
;
;  NOW LOOK AT FULL SWITCHES TO SEE
;  IF DESIRED ZONE HAS AVAILABLE SECTORS
;
HDGS2
	LDX HDCZN       ;GET DESIRED ZONE #
	JSR HDCIND      ;CALC INDEX VALUE
	LDA HDZFUL,X    ;LOOK AT FULL SW.
	BEQ HDGS4       ;JMP IF NOT FULL
HDGS3
	INC HDCZN       ;BUMP TO NEXT ZONE
	LDX DRVNUM      ;GET MAX ON THAT DRIVE
	LDA HDCZN       ;CHK IF AT END OF MEDIA
	CMP HDNZA,X     ;*
	BCC HDGS2       ;IF NOT GO CHK THAT ZONE
;
;  ZONES 1-N ARE FULL
;  TRY ZONE 0 UNLESS WE STARTED THERE
;
	DEC HDTYP       ;CHK REQUEST TYPE
	LDA HDTYP       ;SET PROPER ZONE
	STA HDCZN       ;*
	BEQ HDGS2       ;GO GET FROM ZONE
;
;  GIVE DISK FULL ERROR
;
	LDA #DSKFUL     ;ERROR MSG
	JMP CMDERR      ;EXIT
;
; ALLOCATE A SECTOR FROM THE ZONE
; THE TABLE INDEX IS IN REG X
;
HDGS4
	JSR HDGTS       ;GET A SECTOR
	BEQ HDGS5       ;JMP IF NONE ARE AVAIL
	STA SECTOR      ;SAVE SECTOR #
	STY TRACK       ;SAVE TRACK #
	RTS             ;EXIT TO CALLER
;
;  ZONE IS FULLY ALLOCATED MARK IT & MOVE TO NEXT
;
HDGS5
	LDA #1          ;NZ IS FULL
	STA HDZFUL,X    ;*
	BNE HDGS3       ;JMP
.PAG 'GET A SECTOR'
;  GET A SECTOR FROM THE CALC ZONE INDEX
;
;  ON EXIT:
;    X=CALC ZONE # (UNCHANGED)
;    Z=NO SECTOR AVAILABLE
;    NZ=SECTOR IS ALLOC (SEE A&Y)
;    A=ALLOCATED SECTOR ADDR
;    Y=ALLOCATED TRACK ADDR
;
;  ON ENTRANCE:
;    HDCZN=UNCALCULATED ZONE #
;
HDGTS
	JSR HDISU       ;SET UP INDIRECT WORD
	JSR HDLBM       ;LOAD THE DESIGNATED BAM
	LDY #HDBIT1     ;PT TO FIRST BIT
HDGTS1
	LDA (HDBMP),Y   ;LOOK AT NEXT GROUP OF SECTS.
	BNE HDGTS2      ;JMP IF ANY AVAILABLE
	INY             ;BUMP TO NEXT GROUP
	BNE HDGTS1      ;LOOP TILL WHOLE BAM CHKD
;
;  NONE AVAILABLE IN THIS BAM
;
	RTS             ;EXIT (Z IS SET)
;
;  FOUND SOME AVAILABLE
;  SO CALCULATE THE TRACK & SECTOR ADDR OF ONE OF THEM
;
;
;FIRST CALC THE BIT NUMBER
;
HDGTS2
	LDX #0          ;BIT 0 = LEFTMOST BIT
HDGTS4
	ASL A           ;LOOK AT LEFTMOST
	BCS HDGTS3      ;BR IF BIT IS SET
	INX             ;BUMP THE BIT NUMBER
	BNE HDGTS4      ;JMP
HDGTS3
	STX HDTMP1      ;SAVE THE BIT NUMBER
;
; TURN  THE BIT OFF TO INDICATE
; THAT THE SECTOR HAS BEEN ALLOCATED
;
HDGT4
	LSR A           ;MOVE A ZERO BACK
	DEX             ;KEEP SHIFTING ZEROES BACK IN
	BPL HDGT4       ;LOOP TILL DONE
;
;  PUT BYTE BACK INTO BAM
;
	STA (HDBMP),Y   ;*
;
; CALCULATE THE BYTE NUMBER
;
	TYA             ;BAM INDEX
	SEC             ;PREP FOR SBC
	SBC #HDBIT1     ;INDEX TO FIRST BYTE
	STA HDTMP2      ;SAVE # BYTES
;
; MULTIPLY NUMBER OF BYTES BY 8
;
	LDA #0          ;CLEAR HIGH BYTE
	STA HDTMP3      ;*
	ASL HDTMP2      ;SHIFT LEFT 3
	ROL HDTMP3      ;*
	ASL HDTMP2      ;*
	ROL HDTMP3      ;*
	ASL HDTMP2      ;*
	ROL HDTMP3      ;*
;
; ADD IN THE NUMBER OF BITS
;
	LDA HDTMP1      ;*
	ADC HDTMP2      ;*
	STA HDTMP2
	BCC HDGT5       ;16 BIT ADD
	INC HDTMP3
;
;  HDTMP 2&3 ARE NOW EQ TO #BITS INTO BAM
;
HDGT5
;
;  GET # SECTORS PER CYLINDER
;
	LDY #HDNSEC     ;NUMBER PER SURFACE
	LDA (HDBMP),Y   ;*
	LDX DRVNUM      ;DRIVE NUMBER
	PHA
	LDA HDNSUR,X    ;GET NUMBER OF SURFACES
	AND #HDSURF     ;LEAVE ONLY # SURFS
	TAY
	PLA
	DEY             ;CHK FOR ONLY ONE SURFACE
	BEQ HDGT5A      ;JMP IF ONLY ONE
	ASL A           ;MULT # SECTORS * 2
	DEY             ;CHK IF TWO SURFACES
	BEQ HDGT5A      ;JMP IF TWO SURFACES
	ASL A           ;MULTIPLIES THE # SECT * 4
HDGT5A
	STA HDTMP4      ;SAVE NUMBER OF SECTS. PER CYL
;
;  DIVIDE NUMBER OF BITS DISP INTO
;  BAM BY THE NUMBER OF SECTORS PER
;  CYLINDER TO GIVE THE CYLINDER
;  OFFSET FROM THE FIRST OF THE BAM
;  AND THE REMAINDER IS THE SECTOR WITHIN THE CYL
;
; (ACTUALLY MAX OF 11 BITS IN HDTMP2&3)
; 8 BITS IN HDTMP4&5
; RESULT GOES IN HDTMP1
;
	LDA #0          ;CLEAR HIGH RESULT
	STA HDTMP5      ;*
	STA HDTMP1      ;CLEAR RESULT
	LDA #2          ;SET SHIFT COUNTER INIT=2
	STA HDTMP       ;*
;
;  ALIGN HIGH ORDER BITS
;
HDGT6
	ASL HDTMP4      ;SHIFT 8 LEFT
	INC HDTMP       ;BUMP SHIFT COUNTER
	BCC HDGT6       ;ASSUMES NOT DIV BY 0
	ROL HDTMP5      ;SHIFT THREE MORE TIMES
	ASL HDTMP4      ;*
	ROL HDTMP5      ;*
	ASL HDTMP4      ;*
	ROL HDTMP5      ;*
;
;  NOW SUBTRACT SHIFTED DIVISOR FROM DIVIDEND
;
HDGT7
	SEC             ;PREP FOR SBC
	LDA HDTMP2      ;LOW BYTE OF DIVIDEND
	SBC HDTMP4      ;LOW BYTE OF DIVISOR
	TAX             ;DONT UPDATE YET
	LDA HDTMP3      ;HIGH BYTE DIVIDEND
	SBC HDTMP5      ;HIGH BYTE DIVISOR
	BCC HDGT8       ;BR IF RESULT WENT MINUS
	STA HDTMP3      ;ELSE UPDATE DIVIDEND
	STX HDTMP2      ;*
	INC HDTMP1      ;SET LOW BIT IN RESULT
	BNE HDGT7       ;JMP
;
;  SHIFT DIVISOR RIGHT
;
HDGT8
	LSR HDTMP5      ;*
	ROR HDTMP4      ;*
;
;  DECR SHIFT COUNTER
;
	DEC HDTMP       ;*
	BMI HDGT9       ;JMP IF ALL DONE
;
;  SHIFT RESULT LEFT ONE
;
	ASL HDTMP1      ;*
	JMP HDGT7       ;LOOP TILL DONE
;
; DIVIDE DONE NOW CALC TRACK #
;
HDGT9
	LDY #HDCYL      ;GET BEG CYL #
	LDA (HDBMP),Y   ;*
	CLC             ;PREP FOR ADC
	ADC HDTMP1      ;ADD QUOTIENT
	PHA             ;SAVE TRACK (CYLINDER)
;
;  REMAINDER DIVIDED BY # SECTORS PER SURFACE = HEAD #
;
	LDY #HDNSEC     ;PT TO # SECTS PER SURF
	LDA HDTMP2      ;REMAINDER FROM DIVIDE
	LDX #255        ;RESULT
HDGT10
	SEC             ;PREP FOR SBC
	SBC (HDBMP),Y   ;SUB LOOP
	INX             ;*
	BCS HDGT10      ;LOOP TILL DONE
;
;  X = HEAD NUMBER
;
	ADC (HDBMP),Y   ;MAKE POSITIVE
	ORA HDXLT,X     ;OR HEAD INTO SECTOR #
	STA HDTMP       ;SAVE HEAD & SECTOR
;
; MARK BAM AS MODIFIED & CALC NEW LRC
;
	JSR HDCLRC      ;*
;
;
;  NOW DECREMENT # SECTORS AVAIL
;
	JSR HDDBC       ;DO IT
;
; NOW RETURN NZ,A=SECTOR,Y=CYLINDER,X=INDEX
;
	PLA             ;Y=CYLINDER (TRACK)
	TAY             ;*
	LDX HDCZN       ;ORIG ZONE
	JSR HDCIND      ;CALC INDEX
	LDA HDTMP       ;A=SECTOR (&HEAD)
	CMP #$FF        ;SET NZ
	RTS             ;EXIT TO CALLER
;
HDXLT	.BYT 0,$40,$80,$C0 ;HEAD TRANSLATE
;
;   SEARCH FROM CURRENT T&S TO END OF TRACK
;
SRCHET
	JSR FINDTS      ;SET POINTERS TO CURNT POS.
	LDX SECTOR      ;SAVE SECTOR
	STX HDTMP1      ;*
	STA HDTMP2      ;SAVE BIT
SRCHE1
	LDA (HDBMP),Y   ;GET THE BYTE
	BIT HDTMP2      ;TEST IF AVAILABLE
	BNE SRCHE3      ;BR IF AVAIL
	DEC HDTMPA      ;DEC # SECTORS TO CHECK
	BEQ SRCHE2      ;BR IF DONE WITH SCAN
	INC HDTMP1      ;BUMP CURNT SECTOR
	ROR HDTMP2      ;MOVE MASK BIT TO THE RIGHT
	BNE SRCHE1      ;LOOP TILL DONE/FOUND
	ROR HDTMP2      ;PUT BIT BACK INTO BIT 7
	INY             ;BUMP TO NEXT BYTE
	BNE SRCHE1      ;JMP
SRCHE2
	RTS             ;EXIT NZ=FOUND Z=NOT FOUND
SRCHE3
	LDA HDTMP2      ;BIT MASK
	LDX HDTMP1
	STX SECTOR      ;SECTOR TO USE
	JSR HDCBIK      ;ALLOC SECTOR & GEN LRC
	LDA #1          ;NZ
	RTS
.END