NAME
    blkcpy, copy - copy items from a structure to a structure

SYNOPSIS
    blkcpy(dst, src [, num [, dsi [, ssi]]]
    copy(src, dest [, [ssi [, num [, dsi]]])

TYPES
    src		block, file, string, matrix, or list
    dest	block, file, matrix or list - compatible with src

    ssi		nonnegative integer, defaults to zero
    num		nonnegative integer, defaults to maximum possible
    dsi		nonnegative integer, defaults to datalen for a block, filepos
			for a file, zero for other structures

    return	null if successful, error value otherwise

DESCRIPTION
    A call to:

	blkcpy(dst, src, num, dsi, ssi)

    attempts to copy 'num' consecutive items (octets or values) starting
    from the source item 'src' with index 'ssi'.  By default, 'num'
    is the maximum possible and 'ssi' is 0.

    A call to:

	copy(src, dst, ssi, num, dsi)

    does the same thing, but with a different arg order.

    A copy fails if ssi or num is too large for the number of items in
    the source, if sdi is too large for the number of positions
    available in the destination, or, in cases involving a file stream,
    if the file is not open in the required mode.  The source and
    destination need not be of the same type, e.g. when a block is
    copied to a matrix the octets are converted to numbers.

    The following pairs of source-type, destination-type are permitted:

	block to
		 int
		 block
		 matrix
		 file

	matrix to
		 block
		 matrix
		 list

	string to
		 block
		 file

	list to
		 list
		 matrix

	file to
		 block

	int to
		 block

    In the above table, int refers to integer values.  However if a
    rational value is supplied, only the numerator is copied.

    Each copied octet or value replaces the octet or value in the
    corresponding place in the destination structure.  When copying values
    to values, the new values are stored in a buffer, the old values are
    removed, and the new values copied from the buffer to the destination.
    This permits movement of data within one matrix or list, and copying
    of an element of structure to the structure.

    Except for copying to files or blocks, the destination is already to have
    sufficient memory allocated for the copying.  For example, to copy
    a matrix M of size 100 to a newly created list, one may use:

	; L = makelist(100);
	; copy(M, L);
   or:
	; L = makelist(100);
	; blkcpy(L, M);

    For copying from a block B (named or unnamed), the total number of octets
    available for copying is taken to the datalen for that block,
    so that num can be at most size(B) - ssi.

    For copying to a block B (named or unnamed), reallocation will be
    required if dsi + num > sizeof(B).	(This will not be permitted if
    protect(B) has bit 4 set.)

    For copying from a file stream fs, num can be at most size(fs) - ssi.

    For copying from a string str, the string is taken to include the
    terminating '\0', so the total number of octets available is
    strlen(str) + 1 and num can be at most strlen(str) + 1 - ssi.
    If num <= strlen(str) - ssi, the '\0' is not copied.

    For copying from or to a matrix M, the total number of values in
    M is size(M), so in the source case, num <= size(M) - ssi, and
    in the destination case, num <= size(M) - dsi.  The indices ssi
    and dsi refer to the double-bracket method of indexing, i.e. the
    matrix is as if its elements were indexed 0, 1, ..., size(M) - 1.

EXAMPLE
    ; A = blk() = {1,2,3,4}
    ; B = blk()
    ; blkcpy(B,A)
    ; B
	chunksize = 256, maxsize = 256, datalen = 4
	01020304
    ; blkcpy(B,A)
    ; B
	chunksize = 256, maxsize = 256, datalen = 8
	0102030401020304
    ; blkcpy(B, A, 2, 10)
    ; B
	chunksize = 256, maxsize = 256, datalen = 12
	010203040102030400000102
    ; blkcpy(B,32767)
    ; B
	chunksize = 256, maxsize = 256, datalen = 16
	010203040102030400000102ff7f0000
    ; mat M[2,2]
    ; blkcpy(M, A)
    ; M
	mat [2,2] (4 elements, 4 nonzero):
	  [0,0] = 1
	  [0,1] = 2
	  [1,0] = 3
	  [1,1] = 4
    ; blkcpy(M, A, 2, 2)
    ; M
	mat [2,2] (4 elements, 4 nonzero):
	  [0,0] = 1
	  [0,1] = 2
	  [1,0] = 1
	  [1,1] = 2

    ; A = blk() = {1,2,3,4}
    ; B = blk()
    ; copy(A,B)
    ; B
	chunksize = 256, maxsize = 256, datalen = 4
	01020304
    ; copy(A,B)
    ; B
	chunksize = 256, maxsize = 256, datalen = 8
	0102030401020304
    ; copy(A,B,1,2)
    ; B
	chunksize = 256, maxsize = 256, datalen = 10
	01020304010203040203
    ; mat M[2,2]
    ; copy(A,M)
    ; M
	mat [2,2] (4 elements, 4 nonzero):
	  [0,0] = 1
	  [0,1] = 2
	  [1,0] = 3
	  [1,1] = 4

    ; copy(A,M,2)
    ; M
	mat [2,2] (4 elements, 4 nonzero):
	  [0,0] = 3
	  [0,1] = 4
	  [1,0] = 3
	  [1,1] = 4

    ; copy(A,M,0,2,2)
    ; M
	mat [2,2] (4 elements, 4 nonzero):
	  [0,0] = 3
	  [0,1] = 4
	  [1,0] = 1
	  [1,1] = 2

LIMITS
    none

LINK LIBRARY
    none

SEE ALSO
    blk, mat, file, list, str

## Copyright (C) 1999-2006,2021  Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL.  You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## Under source code control:	1997/04/05 14:08:50
## File existed as early as:	1997
##
## chongo <was here> /\oo/\	http://www.isthe.com/chongo/
## Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/
