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LDB vs LOAD-BYTE
- To: MOON at SCRC-TENEX
- Subject: LDB vs LOAD-BYTE
- From: Glenn S. Burke <GSB at MIT-ML>
- Date: Tue, 21 Dec 1982 22:05:00 -0000
- Cc: common-lisp at SU-AI
Date: Monday, 20 December 1982 21:37-EST
From: MOON at SCRC-TENEX
In-reply-to: The message of 2 DEC 1982 0504-PST from JONL at PARC-MAXC
. . .
and that (LDB (BYTE n-bits position) word) is slightly preferable to the
introduction of a new function LOAD-BYTE, and would generate precisely
the same code in any reasonable VAX compiler.
An unreasonable compiler can too. The NIL compiler can (and does). We
have already broken with the #oPPSS format. More complicated are dealing
with the differences of byte extraction from subsequencing. Integers are
treated as if they have infinite length, normal sequences are not, and
this is where hair arises when attempting to inline code a byte-extract
on a fixnum.