M423 Increment a Byte of a Packed Vector

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M423 Increment a Byte of a Packed Vector

Routine ID: M423
Author(s): J. Zoll, P. Rastl	Library: KERNLIB
Submitter:	Submitted: 28.01.1971
Language: Fortran or Assembler	Revised: 16.09.1991

INCBYT allows incrementing a specified byte of a packed byte vector (cf. PACBYT (M422)).

Structure:

FUNCTION subprogram
User Entry Names: INCBYT

Usage:

    LOST = INCBYT(INC,MX,JX,MPACK)

The 3-word vector MPACK specifies the packing parameters (much like for PACBYT (M422), but

NBITS=0

is not allowed):

MPACK(1): $≡NBITS$ , number of bits per byte.
MPACK(2): $≡INWORD$ , number of bytes per word.
MPACK(3): $≡MAXCAP$ , the maximum capacity of any byte, $≤$ 2**NBITS-1.

INCBYT adds the increment INC into the JX'th byte of the packed byte-vector MX and returns any byte overflow, i.e. the part of INC which cannot be added into the byte, because it now contains MPACK(3).

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M426

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