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Merge branch 'format-float' of github.com:dhylands/micropython into dhylands-format-float

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Damien George 2014-03-10 13:19:55 +00:00
commit 0a8458c353
6 changed files with 359 additions and 20 deletions
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311
py/format-float.c Normal file
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@ -0,0 +1,311 @@
/***********************************************************************
format-float.c - Ruutine for converting a single-precision floating
point number into a string.
The code in this funcion was inspired from Fred Bayer's pdouble.c.
Since pdouble.c was released as Public Domain, I'm releasing this
code as public domain as well.
The original code can be found in https://github.com/dhylands/format-float
Dave Hylands
***********************************************************************/
#include <stdint.h>
#include <stdlib.h>
#include "mpconfig.h"
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
#include "format-float.h"
// 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 FLT_SIGN_MASK 0x80000000
#define FLT_EXP_MASK 0x7F800000
#define FLT_MAN_MASK 0x007FFFFF
static const float g_pos_pow[] = {
1e32, 1e16, 1e8, 1e4, 1e2, 1e1
};
static const float g_neg_pow[] = {
1e-32, 1e-16, 1e-8, 1e-4, 1e-2, 1e-1
};
int format_float(float 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
// nulll.
if (buf_size >= 2) {
*s++ = '?';
}
if (buf_size >= 1) {
*s++ = '\0';
}
return buf_size >= 2;
}
if (num.u & FLT_SIGN_MASK) {
*s++ = '-';
num.u &= ~FLT_SIGN_MASK;
} else {
if (sign) {
*s++ = sign;
}
}
buf_remaining -= (s - buf); // Adjust for sign
if ((num.u & FLT_EXP_MASK) == FLT_EXP_MASK) {
char uc = fmt & 0x20;
if ((num.u & FLT_MAN_MASK) == 0) {
*s++ = 'I' ^ uc;
*s++ = 'N' ^ uc;
*s++ = 'F' ^ uc;
} else {
*s++ = 'N' ^ uc;
*s++ = 'A' ^ uc;
*s++ = 'N' ^ uc;
}
*s = '\0';
return s - buf;
}
if (prec < 0) {
prec = 6;
}
char e_char = 'E' | (fmt & 0x20); // e_char will match case of fmt
fmt |= 0x20; // Force fmt to be lowercase
char org_fmt = fmt;
if (fmt == 'g' && prec == 0) {
prec = 1;
}
int e, e1;
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;
if (num.u == 0) {
e = 0;
if (fmt == 'e') {
e_sign = '+';
} else if (fmt == 'f') {
num_digits = prec + 1;
}
} else if (num.u < 0x3f800000) { // f < 1.0
// Build negative exponent
for (e = 0, e1 = 32; e1; e1 >>= 1, pos_pow++, neg_pow++) {
if (*neg_pow > num.f) {
e += e1;
num.f *= *pos_pow;
}
}
if (num.f < 1.0F && num.f >= 0.9999995F) {
num.f = 1.0F;
} else {
e++;
num.f *= 10.0F;
}
// If the user specified 'g' format, and e is <= 4, then we'll switch
// to the fixed format ('f')
if (fmt == 'f' || (fmt == 'g' && e <= 4)) {
fmt = 'f';
dec = -1;
*s++ = '0';
if (prec + e + 1 > buf_remaining) {
prec = buf_remaining - e - 1;
}
if (org_fmt == 'g') {
prec += (e - 1);
}
num_digits = prec;
if (num_digits) {
*s++ = '.';
while (--e && num_digits) {
*s++ = '0';
num_digits--;
}
}
} else {
// For e & g formats, we'll be printing the exponent, so set the
// sign.
e_sign = '-';
dec = 0;
if (prec > (buf_remaining - 6)) {
prec = buf_remaining - 6;
if (fmt == 'g') {
prec++;
}
}
}
} else {
// Build positive exponent
for (e = 0, e1 = 32; e1; e1 >>= 1, pos_pow++, neg_pow++) {
if (*pos_pow <= num.f) {
e += e1;
num.f *= *neg_pow;
}
}
// If the user specified fixed format (fmt == 'f') and e makes the
// number too big to fit into the available buffer, then we'll
// switch to the 'e' format.
if (fmt == 'f') {
if (e >= buf_remaining) {
fmt = 'e';
} else if ((e + prec + 2) > buf_remaining) {
prec = buf_remaining - e - 2;
if (prec < 0) {
// This means no decimal point, so we can add one back
// for the decimal.
prec++;
}
}
}
if (fmt == 'e' && prec > (buf_remaining - 6)) {
prec = buf_remaining - 6;
}
// If the user specified 'g' format, and e is < prec, then we'll switch
// to the fixed format.
if (fmt == 'g' && e < prec) {
fmt = 'f';
prec -= (e + 1);
}
if (fmt == 'f') {
dec = e;
num_digits = prec + e + 1;
} else {
e_sign = '+';
}
}
if (prec < 0) {
// This can happen when the prec is trimmed to prevent buffer overflow
prec = 0;
}
// We now have num.f as a floating point number between >= 1 and < 10
// (or equal to zero), and e contains the absolute value of the power of
// 10 exponent. and (dec + 1) == the number of dgits before the decimal.
// For e, prec is # digits after the decimal
// For f, prec is # digits after the decimal
// For g, prec is the max number of significant digits
//
// For e & g there will be a single digit before the decimal
// for f there will be e digits before the decimal
if (fmt == 'e') {
num_digits = prec + 1;
} else if (fmt == 'g') {
if (prec == 0) {
prec = 1;
}
num_digits = prec;
}
// Print the digits of the mantissa
for (int i = 0; i < num_digits; ++i, --dec) {
int32_t d = num.f;
*s++ = '0' + d;
if (dec == 0 && prec > 0) {
*s++ = '.';
}
num.f -= (float)d;
num.f *= 10.0F;
}
// Round
if (num.f >= 5.0F) {
char *rs = s;
rs--;
while (1) {
if (*rs == '.') {
rs--;
continue;
}
if (*rs < '0' || *rs > '9') {
// + or -
rs++; // So we sit on the digit to the right of the sign
break;
}
if (*rs < '9') {
(*rs)++;
break;
}
*rs = '0';
if (rs == buf) {
break;
}
rs--;
}
if (*rs == '0') {
// We need to insert a 1
if (rs[1] == '.' && fmt != 'f') {
// We're going to round 9.99 to 10.00
// Move the decimal point
rs[0] = '.';
rs[1] = '0';
if (e_sign == '-') {
e--;
} else {
e++;
}
}
s++;
char *ss = s;
while (ss > rs) {
*ss = ss[-1];
ss--;
}
*rs = '1';
}
if (num.u < 0x3f800000 && fmt == 'f') {
// We rounded up to 1.0
prec--;
}
}
if (org_fmt == 'g' && prec > 0) {
// Remove trailing zeros and a trailing decimal point
while (s[-1] == '0') {
s--;
}
if (s[-1] == '.') {
s--;
}
}
// Append the exponent
if (e_sign) {
*s++ = e_char;
*s++ = e_sign;
*s++ = '0' + (e / 10);
*s++ = '0' + (e % 10);
}
*s = '\0';
return s - buf;
}
#endif

3
py/format-float.h Normal file
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int format_float(float f, char *buf, size_t bufSize, char fmt, int prec, char sign);

9
py/objfloat.c
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@ -12,12 +12,21 @@
#include "runtime0.h"
#if MICROPY_ENABLE_FLOAT
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
#include "format-float.h"
#endif
mp_obj_t mp_obj_new_float(mp_float_t value);
STATIC void float_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
mp_obj_float_t *o = o_in;
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
char buf[32];
format_float(o->value, buf, sizeof(buf), 'g', 6, '\0');
print(env, "%s", buf);
#else
print(env, "%.8g", (double) o->value);
#endif
}
STATIC mp_obj_t float_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {

1
py/py.mk
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@ -32,6 +32,7 @@ PY_O_BASENAME = \
asmthumb.o \
emitnthumb.o \
emitinlinethumb.o \
format-float.o \
parsenumbase.o \
parsenum.o \
runtime.o \

1
stm/mpconfigport.h
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@ -7,6 +7,7 @@
#define MICROPY_ENABLE_GC (1)
#define MICROPY_ENABLE_REPL_HELPERS (1)
#define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_MPZ)
#define MICROPY_ENABLE_FLOAT (1)
#define MICROPY_FLOAT_IMPL (MICROPY_FLOAT_IMPL_FLOAT)
#define MICROPY_PATH_MAX (128)
/* Enable FatFS LFNs

54
stm/printf.c
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@ -11,6 +11,9 @@
#include "lcd.h"
#include "usart.h"
#include "usb.h"
#if MICROPY_ENABLE_FLOAT
#include "format-float.h"
#endif
#define PF_FLAG_LEFT_ADJUST (0x01)
#define PF_FLAG_SHOW_SIGN (0x02)
@ -210,29 +213,40 @@ int pfenv_printf(const pfenv_t *pfenv, const char *fmt, va_list args) {
chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 16, 'A', flags, width);
break;
#if MICROPY_ENABLE_FLOAT
case 'e':
case 'E':
case 'f':
case 'F':
case 'g':
case 'G':
{
// This is a very hacky approach to printing floats. Micropython
// uses %g when using print, and I just wanted to see somthing
// usable. I expect that this will be replaced with something
// more appropriate.
char dot = '.';
mp_float_t d = va_arg(args, double);
int left = (int)d;
int right = (int)((d - (mp_float_t)(int)d) * 1000000.0);
if (right < 0) {
if (left == 0) {
chrs += pfenv_print_strn(pfenv, "-0", 2, flags, width);
} else {
chrs += pfenv_print_int(pfenv, left, 1, 10, 'a', flags, width);
}
chrs += pfenv_print_strn(pfenv, &dot, 1, flags, width);
chrs += pfenv_print_int(pfenv, -right, 0, 10, 'a', PF_FLAG_ZERO_PAD, 6);
} else {
chrs += pfenv_print_int(pfenv, left, 1, 10, 'a', flags, width);
chrs += pfenv_print_strn(pfenv, &dot, 1, flags, width);
chrs += pfenv_print_int(pfenv, right, 0, 10, 'a', PF_FLAG_ZERO_PAD, 6);
char buf[32];
char sign = '\0';
if (flags & PF_FLAG_SHOW_SIGN) {
sign = '+';
}
else
if (flags & PF_FLAG_SPACE_SIGN) {
sign = ' ';
}
float f = va_arg(args, double);
int len = format_float(f, buf, sizeof(buf), *fmt, prec, sign);
char *s = buf;
// buf[0] < '0' returns true if the first character is space, + or -
// buf[1] < '9' matches a digit, and doesn't match when we get back +nan or +inf
if (buf[0] < '0' && buf[1] <= '9' && (flags & PF_FLAG_ZERO_PAD)) {
chrs += pfenv_print_strn(pfenv, &buf[0], 1, 0, 1);
s++;
width--;
len--;
}
if (*s < '0' || *s >= '9') {
// For inf or nan, we don't want to zero pad.
flags &= ~PF_FLAG_ZERO_PAD;
}
chrs += pfenv_print_strn(pfenv, s, len, flags, width);
break;
}
#endif