96 lines
3.4 KiB
Groff
96 lines
3.4 KiB
Groff
.\" $Header$
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.TH EM I
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.ad
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.SH NAME
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em \- calling program for em interpreters
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.SH SYNOPSIS
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em [-t] [+fcp] [loadfile [args ... ...] ]
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.SH DESCRIPTION
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The loadfile ("e.out" if not specified) is opened to read the first 8 word header.
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The format of this header is explained in e.out(V).
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One of these 8 words is a flag word
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specifying the interpreter options requested at compile time.
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The usual setting of these options is +t -f -c -p.
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These options may be overridden at runtime as follows:
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em -t turns the test option of; em +c turns count on ; em +p turns profile
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on ; em +c +p turns both count and profile on.
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Based on these options the name of the appropriate interpreter
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is constructed.
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Two versions exist, one for two byte words and four byte pointers and
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one for four byte words and pointers.
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The information in the header of the e.out file is used by em to select the
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right interpreter for the word size of used in the e.out file.
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.PP
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This interpreter is searched for in /usr/em/lib/int[24]4.
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.PP
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The flags control the following options that can be turned off
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or on by prepending them with - or + respectively:
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.IP t
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run time tests for undefined variables, array bounds etc...
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This option costs a small amount of memory and some time.
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However, it is very useful for debugging.
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.IP p
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profiling of the entire program. The interpreter maintains tables containing
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an estimate of the number of processor state cycles used per source line.
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A processor state cycle is equal to two internal clock cycles.
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This option is expensive in time as well as in memory space.
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The result tables made at run time are dumped in a human readable
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format onto a file named
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em_profile.
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.IP f
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maintain a bit map of all source lines that have been executed.
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This map is written onto a file em_flow .
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This option is almost free in time and space.
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The file is not easy to read.
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Of each procedure only the lines between the first statement and the last
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statement are represented in the bit map.
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Currently this option is not installed in the em tree.
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.IP c
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count line usage in tables that
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contains for every source line the number of times it
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was entered.
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These tables are written onto em_count, a human readable file .
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This option is cheap in time, but costs some in memory space.
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.IP l
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dump the line numbers of the last 64 lines entered onto a file named
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em_last.
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This file will be in a human readable format.
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This option is used simultaneously with the test option.
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.PP
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These flags
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give rise to 5 different interpreters which are in the
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directory /usr/em/lib/int24 or in /usr/em/lib/int44
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for the two byte word or the four byte word options, respectively.
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.PP
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.SH "FILES"
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.IP /usr/em/lib/int[24]4/em_???? 35
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interpreters proper
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.PD 0
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.IP /usr/em/mach/m68k2/int/mloop?
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source of interpreter
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.IP em_profile
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profile data
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.IP em_count
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source line count data
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.IP em_flow
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source line flow data
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.IP em_last
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last lines executed
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.PD
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.SH "SEE ALSO"
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\fIack\fP(I),
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\fIint24\fP(I),
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\fIint44\fP(I)
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.SH BUGS
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Most error messages are self explanatory.
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If runtime flags are turned on it is advisable to try again
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with the default options.
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If the interpreter does not work most probably your particular
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machine has an other format for the system calls then assumed
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in the source.
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In that case adapt source file mloopc to your machine.
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Also the instruction that causes the machine to allocate stack
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space might differ .
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In that case adapt the macro 'claimstack' in deffile.
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.SH AUTHOR
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Freek van Schagen
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