324 lines
9.8 KiB
Groff
324 lines
9.8 KiB
Groff
.TH READ_EM 3 "$Revision$"
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.ad
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.SH NAME
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EM_open, EM_getinstr, EM_close,
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EM_mkcalls\ \-\ a module to read EM assembly code
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.SH SYNOPSIS
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.B #include <em_spec.h>
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.br
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.B #include <em_mnem.h>
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.br
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.B #include <em_pseu.h>
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.br
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.B #include <em_flag.h>
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.br
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.B #include <em_ptyp.h>
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.br
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.B #include <em.h>
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.br
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.B #include <em_comp.h>
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.PP
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.B int EM_open(char* filename)
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.PP
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.B void EM_close(void)
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.PP
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.B int EM_getinstr(struct e_instr *instr)
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.PP
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.B int EM_mkcalls(struct e_instr *instr)
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.PP
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.B char *EM_error;
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.PP
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.B unsigned int EM_lineno;
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.PP
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.B char *EM_filename;
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.PP
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.B int EM_wordsize, EM_pointersize;
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.SH DESCRIPTION
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This package provides routines to read EM assembly code.
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The object is to simplify the program
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writer's task of reading EM assembly code,
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either in compact or human-readable form.
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.PP
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\fIEM_open\fR must be called as initializer of the package.
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If \fIfilename\fR is a null pointer, reading is done from standard input,
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otherwise it is done from the file \fIfilename\fR.
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\fIEM_open\fR returns 1 on success and 0 on failure
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with an error message in \fIEM_error\fR.
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\fIEM_close\fR must be called after all other calls to this package.
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.PP
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\fIEM_getinstr\fR reads an EM instruction, and
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returns it in the structure pointed to by \fIinstr\fR.
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This structure has the following layout:
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.br
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.PP
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.ta \w'struct\ \ \ 'u +\w'struct e_instr *\ \ \ \ \ \ 'u +\w'em_opcode\ \ \ 'u +\w'*emu_string\ \ \ 'u
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.nf
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/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* $Id$ */
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struct e_arg {
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int ema_argtype; /* type of this argument */
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union e_simple_arg {
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arith emu_cst; /* a cst */
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label emu_dlb; /* a numeric data label */
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label emu_ilb; /* an instruction label */
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char *emu_dnam; /* a data label */
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char *emu_pnam; /* a procedure name */
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char *emu_string; /* a string (fcon,icon,ucon,scon) */
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} ema_arg;
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arith ema_szoroff;
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};
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#define ema_cst ema_arg.emu_cst
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#define ema_dlb ema_arg.emu_dlb
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#define ema_ilb ema_arg.emu_ilb
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#define ema_dnam ema_arg.emu_dnam
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#define ema_pnam ema_arg.emu_pnam
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#define ema_nlocals ema_szoroff
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#define ema_string ema_arg.emu_string
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struct e_instr {
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int em_type; /* Type of this instr */
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#define EM_MNEM 256 /* A machine instruction */
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#define EM_PSEU 257 /* A pseudo */
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#define EM_STARTMES 258 /* Start of a MES pseudo */
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#define EM_MESARG 259 /* A member in a MES list */
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#define EM_ENDMES 260 /* End of a MES pseudo */
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#define EM_DEFILB 261 /* An instruction label definition */
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#define EM_DEFDLB 262 /* A numeric data label definition */
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#define EM_DEFDNAM 263 /* A non-numeric data label def */
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#define EM_ERROR 264 /* Recoverable error */
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#define EM_FATAL 265 /* Unrecoverable error */
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#define EM_EOF 266 /* End of file */
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int em_opcode;
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struct e_arg em_arg;
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};
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extern arith
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EM_holsize, EM_bsssize;
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extern int
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EM_holinit, EM_bssinit;
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#define em_ilb em_arg.ema_ilb
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#define em_dlb em_arg.ema_dlb
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#define em_dnam em_arg.ema_dnam
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#define em_argtype em_arg.ema_argtype
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#define em_cst em_arg.ema_cst
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#define em_pnam em_arg.ema_pnam
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#define em_nlocals em_arg.ema_nlocals
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#define em_string em_arg.ema_string
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#define em_off em_arg.ema_szoroff
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#define em_size em_arg.ema_szoroff
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/* arguments for EXC pseudo: */
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#define em_exc1 em_arg.ema_cst
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#define em_exc2 em_arg.ema_szoroff
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extern char
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*EM_error, *EM_filename;
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extern unsigned int
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EM_lineno;
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extern int
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EM_wordsize, EM_pointersize;
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.fi
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.PP
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The named types \fBarith\fR and \fBlabel\fR refer to types on the local machine
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that are suitable for doing arithmetic and storing EM numeric labels
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respectively.
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Common definitions are \fBlong\fR for \fBarith\fR and \fBunsigned int\fR for
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\fBlabel\fR.
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.PP
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The \fIe_instr\fR structure consists of the fields
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\fIem_type\fR, containing the type of this \fIe_instr\fR,
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\fIem_opcode\fR, containing the opcode of an instruction,
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and \fIem_arg\fR, containing a possible argument.
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.PP
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The possible values of
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\fIem_type\fR, defined in <em_comp.h>, are summarized below:
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.br
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.ta \w'EM_STARTMES\ \ \ 'u +\w'em_defdnam\ \ \ 'u
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.di xx
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\ka
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.br
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.di
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.IP "Value Selector" \nau
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Meaning
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.IP "EM_MNEM em_opcode" \nau
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an EM machine instruction.
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.br
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.PD 0
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.IP " em_arg" \nau
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The \fIem_opcode\fR field
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contains the opcode of the instruction, and \fIem_arg\fR may contain an
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argument. If \fIem_argtype\fR indicates that there is no argument,
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\fIem_cst\fR is set to 0.
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.IP "EM_PSEU em_opcode" \nau
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an EM pseudo instruction.
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.IP " em_arg" \nau
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The \fIem_opcode\fR field
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contains the opcode, and \fIem_arg\fR may contain an argument.
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As consecutive CON-pseudos are allocated consecutively, a CON delivered by
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\fIEM_getinstr\fR has exactly one argument.
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If the CON-pseudo read has more, they are delivered as separate CON's.
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The same holds for ROM-pseudos.
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Also, if the length of a string constant exceeds 256 characters, it will be
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delivered as several CON's or ROM's.
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There are two "special" pseudo's, that use other variables, HOL and BSS.
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They use EM_holsize, EM_holinit, EM_bsssize, and EM_bssinit, because those
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arguments do not fit in the \fIe_arg\fR structure, and we want to keep the
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\fIe_arg\fR structure as small as possible.
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The EXC pseudo has its arguments encoded as indicated in the #defines.
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The PRO pseudo has its second argument in \fIem_nlocals\fR. If it is
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-1, it was omitted.
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.IP "EM_STARTMES em_arg" \nau
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the start of a MES pseudo.
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.br
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There is one argument: the message number.
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The other arguments, if any, are delivered as separate EM_MESARG's.
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.IP "EM_MESARG em_arg" \nau
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an argument of a MES pseudo.
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.IP "EM_ENDMES none" \nau
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the end of a MES pseudo.
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.IP "EM_DEFILB em_ilb" \nau
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an instruction label definition.
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.br
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The field \fIem_ilb\fR contains the label (instruction labels are always
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numeric).
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.IP "EM_DEFDLB em_dlb" \nau
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a numeric data label definition.
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.br
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The field \fIem_dlb\fR contains the label.
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.IP "EM_DEFDNAM em_dnam" \nau
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a non-numeric data label definition.
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.br
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The field \fIem_dnam\fR contains the label.
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.IP "EM_ERROR none" \nau
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an error in the input that makes the rest of the data in the structure
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meaningless.
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.br
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\fIEM_error\fR
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contains an error message.
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.IP "EM_FATAL none" \nau
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a fatal error.
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.br
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\fIEM_error\fR contains an
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error message.
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.IP "EM_EOF none" \nau
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end of file
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.PD
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.PP
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The \fIe_arg\fR structure consists of the fields
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the field \fIema_argtype\fR, containing the type of this argument or 0
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if absent,
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the field \fIema_arg\fR, containing the value of the argument,
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and \fIema_szoroff\fR, containing an optional offset or size.
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The possible values of \fIema_argtype\fR, defined in <em_ptyp.h>,
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are summarized below:
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.br
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.ta \w'dlb_ptyp\ \ \ \ 'u +\w'em_opcode\ \ \ 'u
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.di xx
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\ka
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.br
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.di
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.IP "Value Selector" \nau
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Meaning
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.IP "0 none" \nau
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no argument.
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.IP "ilb_ptyp em_ilb" \nau
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an instruction label.
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.PD 0
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.IP "nof_ptyp em_dlb" \nau
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an offset from a numeric data label.
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.IP " em_off" \nau
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The
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\fIem_off\fR field contains the offset and the
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\fIem_dlb\fR field contains the label.
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.IP "sof_ptyp em_dnam" \nau
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an offset from a non-numeric data label.
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.IP " em_off" \nau
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The \fIem_off\fR field contains the offset and the \fIem_dnam\fR field
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contains the label, represented as a string.
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.IP "cst_ptyp em_cst" \nau
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a numeric constant.
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.IP "pro_ptyp em_pnam" \nau
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a procedure name, not including the '$',
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represented as a string.
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.IP "str_ptyp em_string" \nau
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a string constant.
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.IP " em_size" \nau
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The string is found in \fIem_string\fR, represented as a row of bytes, of
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length \fIem_size\fR.
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.IP "ico_ptyp em_string" \nau
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an integer constant.
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.IP " em_size" \nau
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A string representation of the constant is found in \fIem_string\fR.
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It has size \fIem_size\fR bytes on the target machine.
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.IP "uco_ptyp em_string" \nau
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an unsigned constant.
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.IP " em_size" \nau
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A string representation of the constant is found in \fIem_string\fR.
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It has size \fIem_size\fR bytes on the target machine.
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.IP "fco_ptyp em_string" \nau
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a floating constant.
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.IP " em_size" \nau
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A string representation of the constant is found in \fIem_string\fR.
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It has size \fIem_size\fR bytes on the target machine.
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.PD
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.PP
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When an error occurs, \fIEM_error\fR is set to indicate the reason.
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\fIEM_getinstr\fR returns 1 if all goes well, 0 if it does not.
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The EM_ERROR described above is only set when the error
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is serious enough.
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.PP
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The routine \fIEM_mkcalls\fR "translates" the EM instruction indicated
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by \fIinstr\fR
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into calls of the procedural interface defined in \fIem_code\fR(3L).
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It returns 1 if it succeeds, 0 if it fails for some reason. The
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reason can then be found in \fIEM_error\fR.
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The \fIEM_mkcalls\fP routine is obsolete. It is being replaced by the
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.I C_out
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routine of the
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.I em_code
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module.
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.PP
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\fIEM_lineno\fR contains the line number of the last line read by
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\fIEM_getinstr\fR.
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.PP
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\fIEM_filename\fR contains a filename. It usually contains the value
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given as parameter to \fIEM_open\fR, but may have a different value, when
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the input was the result of some preprocessing.
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.PP
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.I EM_wordsize
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and
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.I EM_pointersize
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contain the wordsize and pointersize, but only after the first
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(pseudo-)instruction has successfully been read.
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.SH FILES
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.nf
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~em/modules/h/em.h
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~em/h/em_ptyp.h
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~em/modules/h/em_comp.h
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~em/modules/lib/libread_emk.a: non-checking library for reading compact EM code
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~em/modules/lib/libread_emkV.a: checking library for reading compact EM code
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~em/modules/lib/libread_emeV.a: checking library for reading human-readable EM code
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.fi
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.SH MODULES
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em_code(3), string(3), ~em/lib.bin/em_data.a
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.SH "SEE ALSO"
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em_code(3)
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.br
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A.S. Tanenbaum, H. v Staveren, E.G. Keizer, J.W. Stevenson, "\fBDescription
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of a Machine Architecture for use with Block Structured Languages\fR",
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Informatica Rapport IR-81, Vrije Universiteit, Amsterdam, 1983.
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.SH REMARKS
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All strings must be considered to be contained in a static area, so
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must be copied to be saved.
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.SH BUGS
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As CON's and ROM's may be delivered in several parts, the count fields in
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a static exchange may be wrong.
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.PP
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Please report bugs to the author.
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