From 13151a934d9acf7f376225d758d48af42ca4d8c6 Mon Sep 17 00:00:00 2001 From: Andrew Cagney Date: Fri, 16 Jan 1998 01:09:15 +0000 Subject: [PATCH] Document existence of old (gencode) and new (igen) MIPS ISA simulators. --- sim/mips/README.Cygnus | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/sim/mips/README.Cygnus b/sim/mips/README.Cygnus index 06c5e433830..5b646eff794 100644 --- a/sim/mips/README.Cygnus +++ b/sim/mips/README.Cygnus @@ -1,3 +1,42 @@ +This directory contains two very different simulators: + + o gencode (old) + + Gencode.c outputs a single monolithic file that is + #included by interp.c + + o igen (new) + + The *.igen files are used as inputs to ../igen/igen. + A number of separate, fairly modula files, are created. + +The new simulator has a number of advantages: + + o builtin support for multi-simming (single simulator + image supporting a number of different instruction + set architectures). + + o Easier maintenance. The input files are not confused + by an intermixing with the generator code. + +gencode continues to exist so that old architectures can be emulated. +*.igen should be used when adding new architectures or adding +instructions to an existing ISA. + +Known bugs? + +A mips16 simulator cannot be built using igen. A custom mips16 +engine.c needs to be written. + +In mips.igen, the semantics for many of the instructions were created +using code generated by gencode. Those semantic segments could be +greatly simplified. + + +---- + +Old README.Cygnus ... + > README.Cygnus ------------------------------------------------------------------------------- -- 2.30.2