NAME

       pmParseUnitsStr - parse units specification

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmParseUnitsStr(const char *string, struct pmUnits *out, double *outMult, char **errMsg);

       cc ... -lpcp

DESCRIPTION

       pmParseUnitsStr  is  designed  to  encapsulate  the  interpretation  of  a  units  (dimension  and scale)
       specification in command line switches for use by the PCP client tools.

       This function expects to be called with the unit/scale specification as string.  This specification takes
       the general form produced by pmUnitsStr(3).  Briefly, the format allows /-separated divisor and dividend,
       each listing space-separated dimensions/scales along the space, time, and count axes.  There are  also  a
       few extra possibilities:

       First,  multiple  equivalent sets of keywords are accepted for the time and space dimensions, insensitive
       to case.  For example, "microseconds", "microsecond", "microsec", "us" are considered synonymous, as  are
       "kilobytes", "KB", "KiB", "kiloByte", and so on.

       Second,  units may be offered in any order, e.g., ms kb count x 10^3 or count x 10^3 kb ms.  They may not
       be repeated within the denominator or within the numerator.  Each scale/unit keyword may  be  immediately
       followed by positive or negative exponents, e.g., ^-4.

       Third,  numerical  scaling  factors  may  be  supplied.   These are factored together with implicit scale
       conversions into the final outMult result.

       The out and outMult values must both be allocated before calling pmParseUnitsStr(3).  If  the  conversion
       is  successful,  pmParseUnitsStr  returns 0, and fills in out and outMult with the unit/scales defined by
       the input parameter.  If the argument strings could not be parsed, it returns a negative status code.

EXAMPLES

                            ┌──────────────────────────────────┬────────────────┬─────────┐
                            │             string               │      out       │ outMult │
                            ├──────────────────────────────────┼────────────────┼─────────┤
                            │2 count                           │ {0,1,0,0,0,0}  │ 0.5     │
                            │count / 7.5 nanosecond            │ {0,1,-1,0,0,0} │ 7.5     │
                            │10 kilobytes / 2.5e2 count x 10^3 │ {1,-1,0,1,3,0} │ 25      │
                            │millisecond / second^2            │ {0,0,-1,0,0,3} │ 1000    │
                            │mib/s                             │ {1,0,-1,2,0,3} │ 1       │
                            └──────────────────────────────────┴────────────────┴─────────┘

BUGS

       For  backward  compatibility,  this   interface   interprets   several   traditional   computer   science
       interpretations of space units incorrectly by the International System of Units (SI) standard.

       The accepted unit string - in either singular or plural form - and the pmParseUnitsStr interpretation for
       each    are:    megabyte(mebibyte),    gigabyte(gibibyte),    terabyte(tebibyte),     petabyte(pebibyte),
       exabyte(exbibyte), zettabyte(zebibyte) and yottabyte(yobibyte).

RETURN VALUE

       A  zero status indicates success.  A negative status indicates an error, in which case the errMsg pointer
       will contain a textual error message, which the caller should later free(3).

SEE ALSO

       PMAPI(3), pmUnitsStr(3), pmConvScale(3), and pmLookupDesc(3).