M426 Unpack Full Words into Bytes

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M426 Unpack Full Words into Bytes

Routine ID: M426
Author(s): CDC: J. Blake, G. Beltz, IBM: A. Berglund	Library: KERNLIB
Submitter:	Submitted: 12.06.1972
Language: Fortran or Assembler	Revised: 01.02.1982

BLOW converts a source array containing a record consisting of a continuous string of NBYTES bytes of NBITS bits per byte into a target array of NBYTES full words, right-adjusted with zero-fill. BLOW is the inverse of BUNCH (M436).

Structure:

SUBROUTINE subprogram
User Entry Names: BLOW
External References: UPKCH (M427)

Usage:

    CALL BLOW(SOURCE,TARGET,NBYTES,NBITS)

SOURCE: Source array containing the string of NBYTES bytes.
TARGET: Target array, which must be at least NBYTES full words long.
NBYTES: Number of bytes in the source record ( $0 < NBYTES$ ).
NBITS: Number of bits per byte ( $0 < NBITS ≤nbpw$ , where $nbpw = 60$ on CDC and $= 32$ on IBM).

Restrictions:

The two arrays SOURCE and TARGET must not overlap in any way.

Error handling:

BLOW ignores calls with erroneous parameter values.

Examples:

CDC:

    CALL BLOW(SOURCE,TARGET,200,18)

The array SOURCE contains a record of 200 18-bit bytes, stored contiguously in 60 60-bit words, i.e., a string of 3600 bits. After the completion of the call to BLOW, the array TARGET will contain 200 60-bit words, each containing one 18-bit byte, right-justified with zero-fill.

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M427

Janne Saarela
Mon Apr 3 15:06:23 METDST 1995