ref: 7ff779ff52b3da9c3b4cfee38cd90088ac65d6c3
dir: /sys/man/1/timepic/
.TH TIMEPIC 1 .SH NAME timepic \- troff preprocessor for drawing timing diagrams .SH SYNOPSYS .B timepic [ .I files ] .SH DESCRIPTION .I Timepic is a .IR pic (1) and .IR troff (1) preprocessor for drawing timing diagrams. .I Timepic code is contained between .B .TPS and .B .TPE lines: .IP .EX \&.TPS \f2width\fP \f2row-height\fP \f2statement-list\fP \&.TPE .EE .PP There are two types of .I timepic statements: variable definitions and signal definitions. Variables are defined with the syntax .IP .EX \f2var\fP = \f2expr\fP; .EE .PP where .I expr is an arithmetic expression involving floating-point constants and previously defined variables. Currently only basic arithmetic (\fB+\fR, \fB-\fR, \fB*\fR and \fB/\fR) is supported. Signals are defined with the syntax .IP .EX \f2name\fP \f2events\fP ; .EE .PP where .I name is a name that must be quoted unless it's a valid symbol. \f2Events\fR is a list consisting of the following things: .TP \(bu The current time can be set using an arithmetic expression, that may be followed by a symbol interpreted as a unit. For instance if you defined .B "μs = 1000;" then .B 1μs and .B "(x+2)*3μs" are both valid time expressions. Note that .B x+2μs is interpreted as .B (x+2)μs which may or may not be intended behaviour. .IP A time expression can be preceded by \fP+\fR to mark it as relative to the previous time. The first time is zero. .IP A time expression can be followed by a symbol name in square brackets. The symbol is then defined with the time. .TP \(bu An expression of the form \fP:\fIname\fR creates an `event' at the current time, changing the value of the signal to \fIname\fR. \fIname\fR can be a symbol (which is not evaluated), a numerical constant or a string in single quotes. The values .BR 0 , .BR 1 , .BR x and .B z have special meaning, unless they are quoted. .TP \(bu A pipe symbol .B | draws a vertical dashed line at the next event. .TP \(bu An expression of the form .IB expr { events } evaluates the expression, rounded to the nearest integer, and then repeats the events the specified number of times. It is illegal if the expression evaluates to a negative number. It is also illegal to use absolute times in the events list. It is however legal to nest this construct. .SH EXAMPLES .IP .EX \&.TPS 6 0.4 c=5; clk +5{:1 +.5c:0 +.5c}; data :x 2.3c:DQ 4c|:x; valid :0 2.3c:1 4c:0; ready :0 3.6c:1 4c:0; \&.TPE .EE .SH FILES .B /sys/src/cmd/timepic.c .SH "SEE ALSO" .IR troff (1), .IR pic (1) .SH BUGS Yes.