From 74eb5f7c6f9cdfa215373a01930d84e5e1eefd66 Mon Sep 17 00:00:00 2001 From: Luke Kenneth Casson Leighton Date: Thu, 20 Feb 2020 11:47:21 +0000 Subject: [PATCH] add para about example namespaces that already exist --- isa_conflict_resolution/isamux_isans.mdwn | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/isa_conflict_resolution/isamux_isans.mdwn b/isa_conflict_resolution/isamux_isans.mdwn index 5bd4a122a..d0f85e509 100644 --- a/isa_conflict_resolution/isamux_isans.mdwn +++ b/isa_conflict_resolution/isamux_isans.mdwn @@ -17,6 +17,16 @@ be relevant for a fixed number of instructions at a time. Caveat: allowing such a countdown to cross branch-points is unwise (illegal instruction?) +An example of a pre-existing "namespace" switch that has been in +prevalent use for several decades (SPARC and other architectures): +dynamic runtime selectability of littel-endian / big-endian "meaning" +of instructions by way of a "mode switch" instruction (of some kind). + +That "switch" is in effect a 33rd (hidden) bit that is part of the opcode, +going directly into the mux / decode phase of instruction decode, and +thus qualifies categorically as a "namespace". This proposal both formalises +and generalises that concept. + # Hypothetical Format Note that this is a hypothetical format, yet TBD, where particular attention -- 2.30.2