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README.md: precision is no longer a limitation, hooray!

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Kosma Moczek 2014-04-27 17:38:49 +02:00
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README.md
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@ -34,6 +34,10 @@ to either fixed-point or floating-point format:
* ``minmea_rescale({-123456, 1000}, 10) => -1235`` * ``minmea_rescale({-123456, 1000}, 10) => -1235``
* ``minmea_float({-123456, 1000}) => -123.456`` * ``minmea_float({-123456, 1000}) => -123.456``
The compound type ``struct minmea_float`` uses ``int_least32_t`` internally. Therefore,
the coordinate precision is guaranteed to be at least ``[+-]DDDMM.MMMMM`` (five decimal digits)
or ±20cm LSB at the equator.
## Coordinate format ## Coordinate format
NMEA uses the clunky ``DDMM.MMMM`` format which, honestly, is not good in the internet era. NMEA uses the clunky ``DDMM.MMMM`` format which, honestly, is not good in the internet era.
@ -114,10 +118,6 @@ typing ``make``.
## Limitations ## Limitations
* Fractional numbers are represented as ``int`` internally, which is 32 bits on
most embedded platforms. Therefore, the maximum supported coordinate precision
is ``[+-]DDDMM.MMMMM``. The library does not check for integer overflow at the
moment; coordinates with more precision will not parse correctly.
* Only a handful of frames is supported right now. * Only a handful of frames is supported right now.
* There's no support for omitting parts of the library from building. As * There's no support for omitting parts of the library from building. As
a workaround, use the ``-ffunction-sections -Wl,--gc-sections`` linker flags a workaround, use the ``-ffunction-sections -Wl,--gc-sections`` linker flags