1PMPARSEUNITSSTR(3) Library Functions Manual PMPARSEUNITSSTR(3)
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6 pmParseUnitsStr - parse units specification
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9 #include <pcp/pmapi.h>
10 int pmParseUnitsStr(const char *string, struct pmUnits *out,
12 double *outMult, char **errMsg);
13 cc ... -lpcp
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17 pmParseUnitsStr is designed to encapsulate the interpretation of a
18 units (dimension and scale) specification in command line switches for
19 use by the PCP client tools.
20 This function expects to be called with the unit/scale specification as
22 string. This specification takes the general form produced by pmU‐
23 nitsStr(3). Briefly, the format allows /-separated divisor and divi‐
24 dend, each listing space-separated dimensions/scales along the space,
25 time, and count axes. There are also a few extra possibilities:
26 First, multiple equivalent sets of keywords are accepted for the time
28 and space dimensions, insensitive to case. For example, "microsec‐
29 onds", "microsecond", "microsec", "us" are considered synonymous, as
30 are "kilobytes", "KB", "KiB", "kiloByte", and so on.
31 Second, units may be offered in any order, e.g., ms kb count x 10^3 or
33 count x 10^3 kb ms. They may not be repeated within the denominator or
34 within the numerator. Each scale/unit keyword may be immediately fol‐
35 lowed by positive or negative exponents, e.g., ^-4.
36 Third, numerical scaling factors may be supplied. These are factored
38 together with implicit scale conversions into the final outMult result.
39 The out and outMult values must both be allocated before calling pm‐
41 ParseUnitsStr(3). If the conversion is successful, pmParseUnitsStr re‐
42 turns 0, and fills in out and outMult with the unit/scales defined by
43 the input parameter. If the argument strings could not be parsed, it
44 returns a negative status code.
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47 ┌──────────────────────────────────┬────────────────┬─────────┐
48 │ string │ out │ outMult │
49 ├──────────────────────────────────┼────────────────┼─────────┤
50 │2 count │ {0,1,0,0,0,0} │ 0.5 │
51 │count / 7.5 nanosecond │ {0,1,-1,0,0,0} │ 7.5 │
52 │10 kilobytes / 2.5e2 count x 10^3 │ {1,-1,0,1,3,0} │ 25 │
53 │millisecond / second^2 │ {0,0,-1,0,0,3} │ 1000 │
54 │mib/s │ {1,0,-1,2,0,3} │ 1 │
55 └──────────────────────────────────┴────────────────┴─────────┘
57 For backward compatibility, this interface interprets several tradi‐
58 tional computer science interpretations of space units incorrectly by
59 the International System of Units (SI) standard.
60 The accepted unit string - in either singular or plural form - and the
62 pmParseUnitsStr interpretation for each are: megabyte(mebibyte), giga‐
63 byte(gibibyte), terabyte(tebibyte), petabyte(pebibyte), ex‐
64 abyte(exbibyte), zettabyte(zebibyte) and yottabyte(yobibyte).
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67 A zero status indicates success. A negative status indicates an error,
68 in which case the errMsg pointer will contain a textual error message,
69 which the caller should later free(3).
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72 PMAPI(3), pmUnitsStr(3), pmConvScale(3), and pmLookupDesc(3).
73Performance Co-Pilot PCP PMPARSEUNITSSTR(3)