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Replace Ryu with a C99 port of fast_float #1006

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Merged
byroot merged 2 commits into from
Jun 16, 2026
Merged

Replace Ryu with a C99 port of fast_float #1006

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fdd6674
Replace Ryu with a C99 port of fast_float
byroot Jun 15, 2026
1a55684
fast_float_parser.h: add portable __builtin_clzll
byroot Jun 15, 2026
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6 changes: 3 additions & 3 deletions LEGAL
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,6 @@ ext/json/ext/vendor/jeaiii-ltoa.h::
This file is adapted from https://github.com/jeaiii/itoa
It is licensed under the MIT License

ext/json/ext/vendor/ryu.h::
This file is adapted from the Ryu algorithm by Ulf Adams https://github.com/ulfjack/ryu.
It is dual-licensed under Apache License 2.0 OR Boost Software License 1.0.
ext/json/ext/vendor/fast_float_parser.h::
This file is adapted from the Fast Float C++ library by The fast_float authors https://github.com/fastfloat/fast_float
It is licensed under the MIT License
2 changes: 1 addition & 1 deletion ext/json/ext/parser/depend
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Expand Up @@ -2,6 +2,6 @@
parser.o: $(srcdir)/../fbuffer/fbuffer.h
parser.o: $(srcdir)/../json.h
parser.o: $(srcdir)/../simd/simd.h
parser.o: $(srcdir)/../vendor/ryu.h
parser.o: $(srcdir)/../vendor/fast_float_parser.h
parser.o: parser.c
# AUTOGENERATED DEPENDENCIES END
8 changes: 3 additions & 5 deletions ext/json/ext/parser/parser.c
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@@ -1,5 +1,5 @@
#include "../json.h"
#include "../vendor/ryu.h"
#include "../vendor/fast_float_parser.h"
#include "../simd/simd.h"

static VALUE mJSON, eNestingError, eParserError, Encoding_UTF_8;
Expand Down Expand Up @@ -1111,13 +1111,11 @@ static inline VALUE json_decode_float(JSON_ParserConfig *config, uint64_t mantis
return rb_float_new(negative ? -0.0 : 0.0);
}

// Fall back to rb_cstr_to_dbl for potential subnormals (rare edge case)
// Ryu has rounding issues with subnormals around 1e-310 (< 2.225e-308)
if (RB_UNLIKELY(mantissa_digits > 17 || mantissa_digits + exponent < -307)) {
if (RB_UNLIKELY(mantissa_digits > 18 || mantissa_digits + exponent < -307)) {
return json_decode_large_float(start, end - start);
}

return DBL2NUM(ryu_s2d_from_parts(mantissa, mantissa_digits, (int32_t)exponent, negative));
return DBL2NUM(ffp_s2d(exponent, mantissa, negative));
}

static inline VALUE json_decode_array(JSON_ParserState *state, JSON_ParserConfig *config, long count)
Expand Down
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