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jianglk.darker
7ee447c011
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4 months ago | |
|---|---|---|
| .. | ||
| Makefile | 4 months ago | |
| README.txt | 4 months ago | |
| decode_double.c | 4 months ago | |
| double_conversion.c | 4 months ago | |
| double_conversion.h | 4 months ago | |
| doubleproto.proto | 4 months ago | |
| encode_double.c | 4 months ago | |
| test_conversions.c | 4 months ago | |
README.txt
Nanopb example "using_double_on_avr" ==================================== Some processors/compilers, such as AVR-GCC, do not support the double datatype. Instead, they have sizeof(double) == 4. Because protocol binary format uses the double encoding directly, this causes trouble if the protocol in .proto requires double fields. This directory contains a solution to this problem. It uses uint64_t to store the raw wire values, because its size is correct on all platforms. The file double_conversion.c provides functions that convert these values to/from floats, without relying on compiler support. To use this method, you need to make some modifications to your code: 1) Change all 'double' fields into 'fixed64' in the .proto. 2) Whenever writing to a 'double' field, use float_to_double(). 3) Whenever reading a 'double' field, use double_to_float(). The conversion routines are as accurate as the float datatype can be. Furthermore, they should handle all special values (NaN, inf, denormalized numbers) correctly. There are testcases in test_conversions.c.