diff options
| -rw-r--r-- | py/formatfloat.c | 183 |
1 files changed, 75 insertions, 108 deletions
diff --git a/py/formatfloat.c b/py/formatfloat.c index a801055a6..ac5a74e8f 100644 --- a/py/formatfloat.c +++ b/py/formatfloat.c @@ -24,14 +24,16 @@ * THE SOFTWARE. */ +#include "py/mpconfig.h" +#if MICROPY_FLOAT_IMPL != MICROPY_FLOAT_IMPL_NONE + #include <stdlib.h> #include <stdint.h> #include "py/formatfloat.h" -#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT /*********************************************************************** - Routine for converting a single-precision floating + Routine for converting a arbitrary floating point number into a string. The code in this funcion was inspired from Fred Bayer's pdouble.c. @@ -44,32 +46,67 @@ ***********************************************************************/ +#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT // 1 sign bit, 8 exponent bits, and 23 mantissa bits. // exponent values 0 and 255 are reserved, exponent can be 1 to 254. // exponent is stored with a bias of 127. // The min and max floats are on the order of 1x10^37 and 1x10^-37 +#define FPTYPE float +#define FPCONST(x) x##F +#define FPROUND_TO_ONE 0.9999995F +#define FPDECEXP 32 + #define FLT_SIGN_MASK 0x80000000 #define FLT_EXP_MASK 0x7F800000 #define FLT_MAN_MASK 0x007FFFFF -static const float g_pos_pow[] = { +union floatbits { + float f; + uint32_t u; +}; +static inline int fp_signbit(float x) { union floatbits fb = {x}; return fb.u & FLT_SIGN_MASK; } +static inline int fp_isspecial(float x) { union floatbits fb = {x}; return (fb.u & FLT_EXP_MASK) == FLT_EXP_MASK; } +static inline int fp_isinf(float x) { union floatbits fb = {x}; return (fb.u & FLT_MAN_MASK) == 0; } +static inline int fp_iszero(float x) { union floatbits fb = {x}; return fb.u == 0; } +static inline int fp_isless1(float x) { union floatbits fb = {x}; return fb.u < 0x3f800000; } +// Assumes both fp_isspecial() and fp_isinf() were applied before +#define fp_isnan(x) 1 + +#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE + +#define FPTYPE double +#define FPCONST(x) x +#define FPROUND_TO_ONE 0.999999999995 +#define FPDECEXP 256 +#include <math.h> +#define fp_signbit(x) signbit(x) +#define fp_isspecial(x) 1 +#define fp_isnan(x) isnan(x) +#define fp_isinf(x) isinf(x) +#define fp_iszero(x) (x == 0) +#define fp_isless1(x) (x < 1.0) + +#endif + +static const FPTYPE g_pos_pow[] = { + #if FPDECEXP > 32 + 1e256, 1e128, 1e64, + #endif 1e32, 1e16, 1e8, 1e4, 1e2, 1e1 }; -static const float g_neg_pow[] = { +static const FPTYPE g_neg_pow[] = { + #if FPDECEXP > 32 + 1e-256, 1e-128, 1e-64, + #endif 1e-32, 1e-16, 1e-8, 1e-4, 1e-2, 1e-1 }; -int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, char sign) { +int mp_format_float(FPTYPE f, char *buf, size_t buf_size, char fmt, int prec, char sign) { char *s = buf; int buf_remaining = buf_size - 1; - union { - float f; - uint32_t u; - } num = {f}; - if (buf_size < 7) { // Smallest exp notion is -9e+99 which is 6 chars plus terminating // null. @@ -82,9 +119,9 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha } return buf_size >= 2; } - if (num.u & FLT_SIGN_MASK) { + if (fp_signbit(f)) { *s++ = '-'; - num.u &= ~FLT_SIGN_MASK; + f = -f; } else { if (sign) { *s++ = sign; @@ -92,19 +129,21 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha } buf_remaining -= (s - buf); // Adjust for sign - if ((num.u & FLT_EXP_MASK) == FLT_EXP_MASK) { + if (fp_isspecial(f)) { char uc = fmt & 0x20; - if ((num.u & FLT_MAN_MASK) == 0) { + if (fp_isinf(f)) { *s++ = 'I' ^ uc; *s++ = 'N' ^ uc; *s++ = 'F' ^ uc; - } else { + goto ret; + } else if (fp_isnan(f)) { *s++ = 'N' ^ uc; *s++ = 'A' ^ uc; *s++ = 'N' ^ uc; + ret: + *s = '\0'; + return s - buf; } - *s = '\0'; - return s - buf; } if (prec < 0) { @@ -120,28 +159,28 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha int dec = 0; char e_sign = '\0'; int num_digits = 0; - const float *pos_pow = g_pos_pow; - const float *neg_pow = g_neg_pow; + const FPTYPE *pos_pow = g_pos_pow; + const FPTYPE *neg_pow = g_neg_pow; - if (num.u == 0) { + if (fp_iszero(f)) { e = 0; if (fmt == 'e') { e_sign = '+'; } else if (fmt == 'f') { num_digits = prec + 1; } - } else if (num.u < 0x3f800000) { // f < 1.0 + } else if (fp_isless1(f)) { // Build negative exponent - for (e = 0, e1 = 32; e1; e1 >>= 1, pos_pow++, neg_pow++) { - if (*neg_pow > num.f) { + for (e = 0, e1 = FPDECEXP; e1; e1 >>= 1, pos_pow++, neg_pow++) { + if (*neg_pow > f) { e += e1; - num.f *= *pos_pow; + f *= *pos_pow; } } char first_dig = '0'; char e_sign_char = '-'; - if (num.f < 1.0F && num.f >= 0.9999995F) { - num.f = 1.0F; + if (fp_isless1(f) && f >= FPROUND_TO_ONE) { + f = FPCONST(1.0); if (e > 1) { // numbers less than 1.0 start with 0.xxx first_dig = '1'; @@ -151,7 +190,7 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha } } else { e++; - num.f *= 10.0F; + f *= FPCONST(10.0); } // If the user specified 'g' format, and e is <= 4, then we'll switch @@ -192,10 +231,10 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha } } else { // Build positive exponent - for (e = 0, e1 = 32; e1; e1 >>= 1, pos_pow++, neg_pow++) { - if (*pos_pow <= num.f) { + for (e = 0, e1 = FPDECEXP; e1; e1 >>= 1, pos_pow++, neg_pow++) { + if (*pos_pow <= f) { e += e1; - num.f *= *neg_pow; + f *= *neg_pow; } } @@ -259,17 +298,17 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha // Print the digits of the mantissa for (int i = 0; i < num_digits; ++i, --dec) { - int32_t d = num.f; + int32_t d = f; *s++ = '0' + d; if (dec == 0 && prec > 0) { *s++ = '.'; } - num.f -= (float)d; - num.f *= 10.0F; + f -= (FPTYPE)d; + f *= FPCONST(10.0); } // Round - if (num.f >= 5.0F) { + if (f >= FPCONST(5.0)) { char *rs = s; rs--; while (1) { @@ -313,7 +352,7 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha } *rs = '1'; } - if (num.u < 0x3f800000 && fmt == 'f') { + if (fp_isless1(f) && fmt == 'f') { // We rounded up to 1.0 prec--; } @@ -340,76 +379,4 @@ int mp_format_float(float f, char *buf, size_t buf_size, char fmt, int prec, cha return s - buf; } -#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE - -#include <errno.h> -#include <stdio.h> - -#ifdef _MSC_VER -// For msvc we need to address some quirks in the snprintf implementation: -// - there is no standard snprintf, it is named _snprintf instead -// - 'F' format isn't handled so use 'f' -// - nan and inf are printed as 1.#QNAN and 1.#INF -#include <math.h> -#include <string.h> - -STATIC int copy_with_sign(char *dest, size_t bufSize, const char *value, char sign) { - if (bufSize == 0) { - return 0; - } - size_t numSignChars = 0; - if (sign) { - *dest = sign; - ++numSignChars; - } - // check total length including terminator - size_t length = strlen(value) + 1 + numSignChars; - if (length > bufSize) { - length = bufSize; - } - // length without terminator - --length; - if (length > numSignChars) { - memcpy(dest + numSignChars, value, length - numSignChars); - } - dest[length] = 0; - return length; -} - -#define snprintf _snprintf -#endif - -int mp_format_float(double value, char *buf, size_t bufSize, char fmt, int prec, char sign) { - if (!buf) { - errno = EINVAL; - return -1; - } -#ifdef _MSC_VER - if (isnan(value)) { - return copy_with_sign(buf, bufSize, "nan", sign); - } else if (isinf(value)) { - return copy_with_sign(buf, bufSize, "inf", value > 0.0 ? sign : '-'); - } else { - if (fmt == 'F') { - fmt = 'f'; - } -#endif - char fmt_buf[6]; - char *fmt_s = fmt_buf; - - *fmt_s++ = '%'; - if (sign) { - *fmt_s++ = sign; - } - *fmt_s++ = '.'; - *fmt_s++ = '*'; - *fmt_s++ = fmt; - *fmt_s = '\0'; - - return snprintf(buf, bufSize, fmt_buf, prec, value); -#ifdef _MSC_VER - } -#endif -} - -#endif +#endif // MICROPY_FLOAT_IMPL != MICROPY_FLOAT_IMPL_NONE |