Update of /project/movitz/cvsroot/ia-x86 In directory common-lisp.net:/tmp/cvs-serv29444

Modified Files: README Log Message: *** empty log message *** Date: Sun Jan 30 03:35:16 2005 Author: ffjeld

Index: ia-x86/README diff -u ia-x86/README:1.1 ia-x86/README:1.2 --- ia-x86/README:1.1 Sat Jan 29 08:33:31 2005 +++ ia-x86/README Sun Jan 30 03:35:16 2005 @@ -10,7 +10,7 @@ ## Author: Frode Vatvedt Fjeld frodef@acm.org ## Created at: Sat Jan 29 16:48:42 2005 ## -## $Id: README,v 1.1 2005/01/29 16:33:31 ffjeld Exp $ +## $Id: README,v 1.2 2005/01/30 11:35:16 ffjeld Exp $ ## ######################################################################

@@ -22,7 +22,7 @@ the Movitz compiler. The following documents the most interesting API operators for this package.

-A few terms requires explanation. A "proglist" is a representation of +A few terms requires explanation. A "program" is a representation of an assembly program that is reasonably convenient to work with for humans. This is a list, whose elements are either a symbol that represents a label, or a list that represents an instruction. The @@ -31,10 +31,70 @@ by 1" (more on this syntax below). However, instructions are also represented internally ia-x86 by instances of the various subclasses of the "instruction" standard-class, and lists of such objects are -also someplaces referred to as proglists. +referred to as "proglists".

Assembly

+The function read-proglist reads a program into proglist form, which +is typically the first step in producing machine code. This function +(and its helper functions, in read.lisp) defines the human-readable +syntax for assembly programs. This is an example program (or rather, a +lisp function that produces an assembly program): + + (defun mkasm16-bios-print () + "Print something to the terminal. [es:si] points to the text" + `((:movzxb (:si) :cx) + (:incw :si) + (:movb #xe :ah) + (:movw 7 :bx) + print-loop + (:lodsb) + (:int #x10) + (:loop 'print-loop) + (:ret))) + +I personally tend to use keywords for instruction names, although the +instructions are recognized by name rather than identity, so any +package will do. Labels, however, are recognized by identity. Label +references are on the form (quote <label>), so that the loop +instruction above will transfer control to the print-loop label two +instructions before it. Indirect memory references are writen by +placing the pointer inside parens, such as in the first movzxb above. +If the first element of an instructon is a list (rather than an +instruction name), this is interpreted as a list of instruction +prefixes (such as REP, LOCK, etc.). + +This is a more-or-less exact description of the syntax: + + program ::= (<sexpr>*) + + sexpr ::= ( <expr> ) | <label> | (% <inline-data> %) | (:include . <program>) + expr ::= <instro> | ( { <prefix> } ) <instro> + instro ::= <instruction> { <operand> } + + operand ::= <concrete> | <abstract> + + concrete ::= <immediate> | <register> | <indirect> + immediate ::= <number> + register ::= eax | ecx | ... + indirect ::= ( iexpr ) + iexpr ::= <address> + | (quote <label>) + | <segment> <address> + | pc+ <offset> + | pc <address> + | { (quote <label>) } <offset> <scaled-register> <register> + scaled-register ::= <register> | ( <register> <scale> ) + scale ::= 1 | 2 | 4 | 8 + address ::= <number> + offset ::= <signed-number> + + abstract ::= (quote <absexpr>) + absexpr ::= <label> | <number> | append-prg + append-prg ::= program

+ prefix ::= <segment-override> | (:size <size>)

+The function proglist-encode takes a proglist and produces +machine-code in the form of e.g. a vector of 8-bit bytes.