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+# Introduction
+
+This library provides functions for working with timespec structures.
+
+It aims to provide a comprehensive set of functions with well-defined behaviour
+that handle all edge cases (e.g. negative values) in a sensible manner.
+
+Negative values are allowed in the tv_sec and/or tv_usec field of timespec
+structures, tv_usec is always relative to tv_sec, so mixing positive and
+negative values will produce consistent results:
+
+    { tv_sec = 1,  tv_nsec = 500000000  } ==  1.5 seconds
+    { tv_sec = 1,  tv_nsec = 0          } ==  1.0 seconds
+    { tv_sec = 1,  tv_nsec = -500000000 } ==  0.5 seconds
+    { tv_sec = 0,  tv_nsec = 500000000  } ==  0.5 seconds
+    { tv_sec = 0,  tv_nsec = 0          } ==  0.0 seconds
+    { tv_sec = 0,  tv_nsec = -500000000 } == -0.5 seconds
+    { tv_sec = -1, tv_nsec = 500000000  } == -0.5 seconds
+    { tv_sec = -1, tv_nsec = 0          } == -1.0 seconds
+    { tv_sec = -1, tv_nsec = -500000000 } == -1.5 seconds
+
+Furthermore, any timespec structures processed or returned by library functions
+are normalised according to the rules defined by `timespec_normalise()`.
+
+A test program for your platform can be produced by compiling with `-DTEST`.
+
+This is public domain. Feel free to embed it in your software if it meets your
+needs.
+
+# Functions
+
+## Maths functions
+
+`struct timespec timespec_add(struct timespec ts1, struct timespec ts2)`
+
+Returns the result of adding two timespec structures.
+
+`struct timespec timespec_sub(struct timespec ts1, struct timespec ts2)`
+
+Returns the result of subtracting ts2 from ts1.
+
+`struct timespec timespec_mod(struct timespec ts1, struct timespec ts2)`
+
+Returns the remainder left over after dividing ts1 by ts2.
+
+## Clamping
+
+`struct timespec timespec_min(struct timespec ts1, struct timespec ts2);`
+
+Return the lesser one of the two given timespec values.
+
+`struct timespec timespec_max(struct timespec ts1, struct timespec ts2);`
+
+Return the greater one of the two given timespec values.
+
+`struct timespec timespec_clamp(struct timespec ts1, struct timespec min, struct timespec max);`
+
+Clamp the value of TS between MIN and MAX.
+
+## Comparison functions
+
+`int timespec_cmp(struct timespec ts1, struct timespec ts2)`
+
+Returns (1, 0, -1) if ts1 is (greater than, equal to, less than) ts2.
+
+`bool timespec_eq(struct timespec ts1, struct timespec ts2)`
+
+Returns true if the two timespec structures are equal.
+
+`bool timespec_gt(struct timespec ts1, struct timespec ts2)`
+
+Returns true if ts1 is greater than ts2.
+
+`bool timespec_ge(struct timespec ts1, struct timespec ts2)`
+
+Returns true if ts1 is greater than or equal to ts2.
+
+`bool timespec_lt(struct timespec ts1, struct timespec ts2)`
+
+Returns true if ts1 is less than ts2.
+
+`bool timespec_le(struct timespec ts1, struct timespec ts2)`
+
+Returns true if ts1 is less than or equal to ts2.
+
+## Conversion funtions
+
+`struct timespec timespec_from_double(double s)`
+
+Converts a fractional number of seconds to a timespec.
+
+`double timespec_to_double(struct timespec ts)`
+
+Converts a timespec to a fractional number of seconds.
+
+`struct timespec timespec_from_timeval(struct timeval tv)`
+
+Converts a timeval to a timespec.
+
+`struct timeval timespec_to_timeval(struct timespec ts)`
+
+Converts a timespec to a timeval.
+
+`struct timespec timespec_from_ms(long milliseconds)`
+
+Converts an integer number of milliseconds to a timespec.
+
+`long timespec_to_ms(struct timespec ts)`
+
+Converts a timespec to an integer number of milliseconds.
+
+## Normalisation
+
+`struct timespec timespec_normalise(struct timespec ts)`
+
+Returns a normalised version of a timespec structure, according to the following
+rules:
+
+1. If tv_nsec is >=1,000,000,00 or <=-1,000,000,000, flatten the surplus
+   nanoseconds into the tv_sec field.
+
+2. If tv_nsec is negative, decrement tv_sec and roll tv_nsec up to represent
+   the same value attainable by ADDING nanoseconds to tv_sec.