stringtofloat

Minimal dependency, easy to understand string to floating point number conversion.

Requirements

C compiler with unsigned 64-bit integer type and basic arithmetic on it (comparision, addition, subtraction, bit shifts).
<stdint.h> header file or its equivalent defining int32_t, uint32_t, uint64_t types.
It is assumed that int type is at least 16-bit wide.
Size of other types and system endianess are not important.
The C standard library is not required, unless a compiler needs it to provide the above features.
No other libraries are required.

Converts an ASCII string to IEEE 754 double precision number.
Supports scientific notation, all common abbreviations (no zero before dot, ommitted plus signs).
The code is easy to understand, algorithm is explained in details.
The code is splitted into parser and converter parts, which are independent. Parser is easy to modify to support non-ASCII or wide chars.
Parser reads character by character, so can work with pipe style inputs. There is no limit for length of string, string is not buffered.
Small in size. On most platforms the compiled code is less than 2 kB.
Uses no floating point arithmetic by itself.
Covers full range of double precision numbers with precise limit checking.
Numbers out of range are converted to infinity with proper sign.
Very small numbers are converted to zero with proper sign.

No support for explicit "+Inf", "-Inf", "NaN" strings.
Denormalized floats are never generated, zero of proper sign is returned instead.
The rounding mode is always round towards zero.