perm filename PACK.TXT[HAK,ROB] blob sn#432333 filedate 1979-04-10 generic text, type C, neo UTF8
COMMENT āŠ—   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	The problem:
C00004 ENDMK
CāŠ—;
The problem:
  Devise a sequence of PDP-10 instructions which map the folllowing bits:
    ABCDEFGHIJKLMNOPxx,,abcdefghijklmnopxx
  into:
    xxxxABCDEFGHIJKLMN,,OPabcdefghijklmnop

  You may assume the number to be on AC1,  and other ACs are available.

	SOJGE	AC3,LOOP	;; just loop to give us a control case
;   Total,Increment,Wait,PS,EBOX msec,Incr=
;      0:17'38,   0:00'53,   1:44'23,246,7942,640

	DPB	1,PNT		;; shove the right half leftwards two bits
	ASH	1,-4		;; and slam the entire word back right 4 bits
	SOJGE	AC3,LOOP	;; and loop
;   Total,Increment,Wait,PS,EBOX msec,Incr=
;      0:12'28,   0:03'59,   1:03'02,186,6333,2804

	LSHC	1,-=20		;; our lsb of LH ā†’ lsb of RH
	LSH	2,2		;; our msb of RH nuzzles up to it
	LSHC	1,=16		;; shove it all back in place
	SOJGE	AC3,LOOP	;; and loop
;   Total,Increment,Wait,PS,EBOX msec,Incr=
;      0:34'39,   0:03'54,   3:03'58,416,15679,3244

	HLLZ	AC2,AC1		;; 
	LSHC	AC1,-2		;;
	LSH	AC2,-2		;;
	HRRZ	AC1,AC1		;;
	OR	AC1,AC2		;;
	SOJGE	AC3,LOOP	;; and loop
;   Total,Increment,Wait,PS,EBOX msec,Incr=
;      0:51'51,   0:04'45,   4:11'31,574,24346,3805