;	m4pkt/asm
;
;	Most of the code in this file was derived directly from
;	the C-KERMIT program.  The code here represents a line by
;	line translation of the C-KERMIT code.
;
MEMSTR	DW	0
MAXSIZE	DB	0
;
;	Encode a packet from memory contents instead of from a file
;
ENCSTR	EQU	$
	PUSH	HL		;Save the registers
	PUSH	BC
	PUSH	DE
	LD	(MEMSTR),HL	;Store the passed pointer
	CALL	RSETPKT		;Reinitiaize GETPKT() parameters
	CALL	GETPKT		;Get a packet
	LD	HL,0		;Reset the memory pointer
	LD	(MEMSTR),HL
	POP	DE		;Restore the registers
	POP	BC
	POP	HL
	RET			;Return to the caller
;
;	Get a packet worth of data from the FILE indicated by the global
;	FCB.  Eighth bit quoting, and Repeat count prefixing are done
;	as indicated by the status of EBQFLAG, and RPTFLG respectively.
;
GETPKT	EQU	$
	PUSH	BC		;Save the registers
	PUSH	DE
	PUSH	HL
	LD	A,(CURCHK)	;Calculate the size of a packet
	SUB	'1'
	LD	B,A
	LD	A,(SPSIZ)	;Get the user specified size
	SUB	5		;Minus the overhead
	SUB	B
	LD	(MAXSIZE),A	;Save it for later use
	LD	HL,(NEXT)	;Get the next character, 16 bits
	LD	BC,0		;Subtract zero to set flags
	OR	A		;Reset the carry flag
	SBC	HL,BC		;Set the flags
	JP	P,GETPKT1
	CALL	GETCH		;Get a character if no previous exists
	LD	(CH),HL		;Save it
GETPKT1	EQU	$
	LD	BC,0		;Copy leftovers from previous call
GETPKT2	EQU	$
	LD	HL,LEFTOVER	;Get the start
	ADD	HL,BC		;Index by BC
	LD	A,(HL)		;Get a byte
	LD	HL,FILBUF	;Get the destination
	ADD	HL,BC		;Index by BC
	LD	(HL),A		;Put a byte
	IFZ	GETPKT3		;Exit loop if zero byte found
	INC	C		;Point to next
	JR	GETPKT2		;Loop on
GETPKT3	EQU	$
	LD	A,C		;Save the initial size of leftovers
	LD	(SIZE),A
	XOR	A		;Nullify the string for next time
	LD	(LEFTOVER),A
GETPKT4	EQU	$
	LD	HL,(CH)		;Get the character
	LD	BC,0		;Subtract zero to set the flags
	OR	A
	SBC	HL,BC
	JP	M,GETPKT20	;Jump at end of file
	CALL	GETCH		;Get the next character
	LD	(NEXT),HL	;Save it
	LD	A,(SIZE)	;Get the current size
	LD	(OSIZE),A	;Save it in case we overflow the packet
	LD	C,A		;Make BC a 16 bit value of C
	LD	B,0
	LD	HL,FILBUF	;Get the desination buffer
	ADD	HL,BC		;Index by BC
	LD	(CBFPTR),HL	;Save the buffer pointer
	LD	HL,(CH)		;Get the character
	LD	A,L		;Keep only 8 bits
	CALL	ENCODE		;Encode it and store the result
	LD	HL,(CBFPTR)	;Compute the new size
	LD	BC,FILBUF	;Get the start
	OR	A		;Reset carry
	SBC	HL,BC		;Compute lenght
	LD	A,L		;Keep only 8 bits
	LD	(SIZE),A	;Store the result
	LD	HL,(NEXT)	;Get the next character
	LD	(CH),HL		;Store it as the current character
	LD	A,(SIZE)	;Get the size and check the size
	LD	C,A
	LD	A,(MAXSIZE)	;Get the maximum length
	CP	C		;Are they equal?
	JP	Z,GETPKT20	;Go return SIZE if equal
	JP	P,GETPKT13	;Jump if maxsize still bigger
	LD	BC,0		;Start from the beginning
GETPKT11	EQU	$
	LD	A,(OSIZE)	;Get the oldsize index
	PUSH	BC		;Save the value of i
	ADD	A,C		;Compute osize+i
	LD	C,A		;Save the result
	LD	HL,FILBUF	;Get the start of the buffer
	ADD	HL,BC		;Compute &filbuf[osize+i]
	LD	A,(HL)		;Get the character stored there
	POP	BC		;Restore i
	LD	HL,LEFTOVER	;Get the address of the leftover buffer
	ADD	HL,BC		;Compute the absolute address
	LD	(HL),A		;Store the byte
	OR	A		;Check the value for zero
	JR	Z,GETPKT12	;Jump if end of string
	INC	C		;Compute i++
	JR	GETPKT11	;Go to the top of the loop
GETPKT12	EQU	$
	LD	A,(OSIZE)	;Store the new pointer
	LD	(SIZE),A
	LD	C,A		;Terminate the string with a NULL
	LD	B,0		;Get a 16 bit offset
	LD	HL,FILBUF	;Get the starting address
	ADD	HL,BC		;Compute the address
	LD	(HL),0		;Put in the NULL
	JP	GETPKT20	;Go to the return code
GETPKT13	EQU	$
	JP	GETPKT4
GETPKT20	EQU	$
	LD	A,(SIZE)	;Get the size to return
	POP	HL		;Restore the registers
	POP	DE
	POP	BC
	RET
;
;	Encode the character in the Accumlator and put it into
;	the packet buffer at CBFPTR.
;
ENCODE	EQU	$
	PUSH	BC		;Save the regs
	PUSH	DE
	PUSH	HL
	LD	C,A		;Save the character to encode
	LD	A,(RPTFLG)	;Is repeat quoting in effect?
	OR	A
	JP	Z,ENCODE30
	LD	HL,(NEXT)	;Get the last character
	LD	A,L
	IFANOT	C,ENCODE3
	LD	A,(RPTCNT)	;Get the current repeat count
	INC	A		;Add one to it
	LD	(RPTCNT),A	;Store it back
	CP	94		;Too many characters?
	JP	M,ENCODE50
	LD	A,(RPTQ)
	CALL	PUTCBF
	LD	A,(RPTCNT)
	TOCHAR
	CALL	PUTCBF
	XOR	A
	LD	(RPTCNT),A
	JP	ENCODE30
ENCODE3	EQU	$
	LD	A,(RPTCNT)
	IFANOT	1,ENCODE7
	XOR	A
	LD	(RPTCNT),A
	LD	A,C		;Get the character back
	CALL	ENCODE		;Encode it again
	LD	HL,(CBFPTR)	;Get the buffer pointer
	LD	DE,FILBUF	;Get the start of the buffer
	OR	A		;Reset the carry
	SBC	HL,DE		;Compute the difference	in L
	LD	A,(MAXSIZE)	;Get MAXSIZE
	CP	L		;Is L <= A?
	JP	M,ENCODE6
	LD	A,L		;Get SIZE
	LD	(OSIZE),A	;Store it in the old size
ENCODE6	EQU	$
	XOR	A
	LD	(RPTCNT),A
	LD	A,C		;Get the character back
	CALL	ENCODE		;Encode it
	JP	ENCODE50
ENCODE7	EQU	$
	LD	A,(RPTCNT)
	CP	2
	JP	M,ENCODE10
	LD	A,(RPTQ)
	CALL	PUTCBF
	LD	A,(RPTCNT)	;Get the count
	ADD	A,' '+1		;Uncontrolify it
	CALL	PUTCBF
	XOR	A
	LD	(RPTCNT),A
ENCODE10	EQU	$
ENCODE30	EQU	$
	LD	A,C		;Get the character
	AND	127		;Turn off high bit
	LD	B,A		;Save it
	LD	A,C		;Get the character
	AND	128		;Leave only high bit
	LD	D,A		;Save it
	IFZ	ENCODE32
	LD	A,(EBQFLG)
	IFZ	ENCODE32
	LD	A,(EBQ)
	CALL	PUTCBF
	LD	C,B		;Save only 7 bit version
ENCODE32	EQU	$
	LD	A,C		;Get all bits for check
	IFA	127,ENCODE33
	IFAGE	' ',ENCODE34
ENCODE33	EQU	$
	LD	A,(MYCTLQ)
	CALL	PUTCBF
	LD	A,C		;Get the character
	ADD	A,64		;Uncontrolify it
	AND	127		;Keep only 7 bits
	LD	C,A		;Save the new value
ENCODE34	EQU	$
	LD	HL,(CBFPTR)	;Do this ahead to save overhead
	LD	A,(MYCTLQ)
	IFANOT	B,ENCODE35
	PUTHL	A		;Store the byte
ENCODE35	EQU	$
	LD	A,(RPTFLG)
	IFZ	ENCODE36
	LD	A,(RPTQ)
	IFANOT	B,ENCODE36
	LD	A,(MYCTLQ)
	PUTHL	A
ENCODE36	EQU	$
	LD	A,(EBQFLG)
	IFZ	ENCODE37
	LD	A,(EBQ)
	IFANOT	B,ENCODE37
	LD	A,(MYCTLQ)
	PUTHL	A
ENCODE37	EQU	$
	PUTHL	C
	LD	(CBFPTR),HL
	LD	(HL),0
ENCODE50	EQU	$
	POP	HL		;Restore the stack
	POP	DE
	POP	BC
	RET
;
;	Decode the contents of the packet, and output them using
;	the function whose address is passed in HL
;
DECODE	LD	(OUTADDR),HL	;Save the output function
	PUSH	BC		;Save the registers that we use
	PUSH	DE
	PUSH	HL
	LD	HL,DATA		;Get the buffer address
	LD	(DATPTR),HL	;Set the address
	LD	C,A		;Get the length
	LD	B,0		;Make it 16 bits
	PUSH	HL		;Save DATPTR
	ADD	HL,BC		;Compute the end of the packet
	LD	(HL),0		;Put in the NULL byte
	POP	HL		;Get DATPTR back
DECODE0	LD	A,1		;Set the repeat count
	LD	(RPTCNT),A
	LD	A,(HL)		;Get a character
	INC	HL		;Point to the next
	LD	C,A		;Store the value
	OR	A		;Is it NULL?
	JP	Z,DECODE40	;Quit the loop if it is
	LD	A,(RPTFLG)	;Is repeat prefixing on?
	IFZ	DECODE1
	LD	A,(RPTQ)	;Get the quote character
	IFANOT	C,DECODE1
	LD	A,(HL)		;Get the count + 32
	SUB	' '		;Make it the real count
	INC	HL		;Point to next character
	LD	(RPTCNT),A	;Save the repeat count
	LD	A,(HL)		;Get a character
	INC	HL		;Point to the next
	LD	C,A		;Save the character
DECODE1	XOR	A		;Set the initial eighth bit as ZERO
	LD	D,A
	LD	A,(EBQFLG)	;Is eighth bit quoting on?
	IFZ	DECODE2
	LD	A,(EBQ)		;Get the eighth bit quote character
	IFANOT	C,DECODE2
	LD	D,128		;Get an eighth bit
	LD	A,(HL)		;Get a character
	INC	HL		;Point to the next
	LD	C,A		;Save the character
DECODE2	LD	A,(MYCTLQ)	;Get the control character quote
	IFANOT	C,DECODE5
	LD	A,(HL)		;Get a character
	INC	HL		;Point to the next
	LD	C,A		;Save the character
	AND	127		;Keep 7 bits
	LD	E,A		;Save only 7 bits worth
	LD	A,E		;Check lower bound of controls
	CP	'@'
	JP	M,DECODE3	;Jump if less than
	CP	96		;Check upper bound of controls
	JP	M,DECODE4
DECODE3	IFANOT	'?',DECODE5
DECODE4	LD	A,C		;Get the character
	SUB	64		;Subtract 64 to uncontrolify it
	AND	127
	LD	C,A		;Save the new value
DECODE5	LD	A,D		;Get the eighth bit
	OR	C		;Or in the character
	LD	C,A		;Save the new value
	LD	A,(RPTCNT)	;Get the repeat count
	LD	B,A		;Get it into the counter
DECODE8	LD	IX,RTRANS	;Get the pointer
	CALL	INCKTRANS	;Increment character counts
	LD	A,C		;Get the character
	CALL	PUTCH
	JR	NZ,DECODE50
	DJNZ	DECODE8		;Loop until done
	JP	DECODE0
DECODE40	EQU	$
	POP	HL		;Restore the stack
	POP	DE
	POP	BC
	RET
DECODE50	EQU	$
	CALL	XERROR0		;Print a system error message
	LD	A,1		;Set NZ status for return
	OR	A
	JR	DECODE40	;Join the exit code
;
;	Get the next character from the input file.  We translate CR to
;	CRLF, for ASCII files.  Returns with (EOFLAG) set to 0FFH at end
;	of file.  The character retrieved is in HL.  HL will be 16bits
;	of -1 and EOF, but will otherwise only be 8bits wide.  H in this
;	case will always be 0, and L will hold the character.
;
GETCH	LD	A,(FILTYPE)	;Check for binary mode
	OR	A		;Set the flags
	JR	NZ,GETCH1	;Jump if it is binary
	LD	A,(PREVCH)	;Get the previous character
	IFANOT	CR,GETCH1
	LD	A,10		;Get a LF character
	LD	(PREVCH),A	;Reset the previous character
	LD	L,A		;Put it into HL
	LD	H,0
	RET			;Return to the caller
GETCH1	EQU	$
	LD	HL,(MEMSTR)
	LD	A,H
	OR	L
	JR	Z,GETCH2
	LD	A,(HL)
	INC	HL
	LD	(MEMSTR),HL
	IFZ	GETCH4
	JR	GETCH3
GETCH2	EQU	$
	LD	DE,FCB		;Get the File Control Block
	CALL	XGET		;Get a character into A
	JR	NZ,GETCH4	;Jump to EOF on error
	LD	IX,STRANS	;Get the pointer
	CALL	INCKTRANS	;Increment the character count
GETCH3	EQU	$
	LD	(PREVCH),A	;Set the previous character
	LD	L,A		;Put it into HL
	LD	H,0
	RET			;Return
GETCH4	EQU	$
	LD	A,0FFH		;Set the EOF flag
	LD	(EOFLAG),A
	LD	(PREVCH),A	;Reset the previous character flag
	LD	L,A		;Make HL 16bits wide -1
	LD	H,A
	RET			;Return to caller
;
;	Put the next character to the output file.  We convert CRLF to CR
;	IFF X packets are not active, and binary mode is not active
;
PUTCH	PUSH	HL
	PUSH	BC		;Save the register
	LD	C,A		;Save the character to output
	LD	A,(PREVCH)	;Get the previous character
	IFANOT	CR,PUTCH1
	LD	A,(DISFLG)	;Check if we are doing X packets
	IFZ	PUTCH1
	LD	A,(FILTYPE)	;Doing D packets, so check file mode
	OR	A
	JR	NZ,PUTCH1
	LD	A,C
	IFA	10,PUTCH2
PUTCH1	LD	A,C		;Get the character to output
	LD	(PREVCH),A	;Make it the new previous
	LD	HL,(OUTADDR)	;Get the output routines address
	CALL	CALLHL		;Call the output routine
PUTCH2	POP	BC		;Restore the stack
	POP	HL
	RET			;Return to caller
;
;	Put A into the location pointed to by CBFPTR, and increment the
;	pointer to point to the next location
;
PUTCBF	LD	HL,(CBFPTR)	;Get the pointer
	PUTHL	A
	LD	(CBFPTR),HL	;Store the new pointer value
	RET			;Return
;end of file