COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	A fast find command using Gosper's scheme
C00007 ENDMK
C⊗;
;A fast find command using Gosper's scheme
PLONG:	0			;Pattern length
FTABLE:	BLOCK 177		;To hold pointer indexing commands
	JRST RELOAD		;To reload buffer and test for end of file

FOLD:	BLOCK 32		;Space to hold last 26 words from previous load
FBUF:	BLOCK 200		;Loaded with record from file
REPEAT 32,<-2>			;Guard for possible pattern length of 128 chars.

FLOOP:	ILDB C,A			;Get next character from file
	XCT @FTABLE(C)

;Code from this list is used for storing in FTABLE
;It is accessed indexed as to the distance from the last char of the pattern to the
;last occurance of the character in the pattern as identified by the position
;in FTABLE that is being loaded. All characters not in the pattern are assumed
;to  be at the pattern-length distance.

FLOAD:	JRST BACK1		;0	Found last char match
	JRST FLOOP		;1	Get next character and start at FLOOP
	JRST FLOAD1		;2	Index over 1 and then get next
	JRST FLOAD2		;3	Jump over 2 and then get next
	JRST FLOAD3		;4	Jump over 3 and then get next
	JRST FLOAD5		;5	Jump over 4 and then get next
FLOAD5:	AOJA A,FLOOP		;6	Jump over 5 and then get next
	AOJA A,FLOAD1		;7
	AOJA A,FLOAD2		;10
	AOJA A,FLOAD3		;11
	AOJA A,FLOAD4		;12
	AOJA A,FLOAD5		;13
	JRST FLOAD5		;16
	JRST FLOAD6		;17
	JRST FLOAD7		;20
	JRST FLOA10		;21
	JRST FLOA11		;22
	JRST FLOA12		;23
	JRST FL0A13		;24
	JRST FLOA14		;25

FLOAD1:	IBP A
	JRST FLOOP

FLOAD2:	SUB A,[160000,,0]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOAD3:	SUB A,[250000,,0]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOAD4:	SUB A,[340000,,0]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

;Code to compute addition for dirtance greater than 13

FLOAD6:	ADDI A,[-70000,,2]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOAD7:	ADDI A,[-160000,,2]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOA10:	ADDI A,[-250000,,2]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOA11:	ADDI A,[-340000,,2]
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP

FLOA12:	ADDI A,3
	JRST FLOOP

;Code to compute value to store in FTABLE 
COMP:	MOVNI T,PNUM
	HRLZS T
	MOVE A,[440700,,PATTER]
 	MOVE TT,T
COMP1:	ILDB C,A
	MOVE B,A
	IBP B
COMP2:	ILDB D,B
	CAMN D,C
	JRST COMP3
	AOBJN TT,COMP2
	MOVE B,LIST(TT)
	MOVEM B,FTABLE(C)
	JRST COMP1

COMP3:	MOVE T,TT
	MOVE A,D
	JRST COMP1


ZZZ:	
	
	Code to preload code referenced by FTABLE for all characters not in PATTERN
	MOVE T,[JRST NOTIN]
	MOVEM T,FTABLE
	MOVEM A,[FTABLE,,FTABLE+1]
	BLT A,FTABLE+177

;Code to compute value to be used by code NOTIN
	MOVE T,PLONG
	SUBI T,1	;There will always be an ILDB
	IDIVI T,5
	IMULI TT,7
	LSH TT,26
	SUB T,TT
	MOVEM T,PSHIFT

;Code referenced when char. is not in PATTERN
NOTIN:	ADD A,PSHIFT
	JUMPG A,FLOOP
	ADDI A,[430000,,1]
	JRST FLOOP