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ANSI Common Lisp  12 Numbers 12.2 Dictionary of Numbers
- Syntax:
-
dpb
newbyte bytespec integer
 result-integer
- Pronunciation:
-
[ 'dE'pib ]
or [ 'dE'pEb ]
or [ 'dê'pê'bê ]
- Arguments and Values:
-
newbyte - an integer.
bytespec - a byte specifier.
integer - an integer.
result-integer - an integer.
- Description:
-
dpb (deposit byte) is used to
replace a field of bits within integer.
dpb returns an integer that is
the same as integer except in the bits specified by bytespec.
Let s be the size specified
by bytespec; then the low s bits of newbyte appear in
the result in the byte specified by bytespec.
Newbyte is interpreted as
being right-justified, as if it were the result of ldb.
- Examples:
-
(dpb 1 (byte 1 10) 0) 1024
(dpb -2 (byte 2 10) 0) 2048
(dpb 1 (byte 2 10) 2048) 1024
- See Also:
-
byte, deposit-field, ldb
- Notes:
-
(logbitp j (dpb m (byte s p) n))
==(if (and (>= j p) (< j (+ p s)))
(logbitp (- j p) m)
(logbitp j n))
In general,
(dpb x (byte 0 y) z) z
for all valid values of x, y, and z.
Historically, the name "dpb" comes from a DEC PDP-10 assembly language
instruction meaning "deposit byte."
- Allegro CL Implementation Details:
-
None.
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