New private API functions _PyFloat_{Pack,Unpack}(4,8}. This is a
refactoring to get all the duplicates of this delicate code out of the
cPickle and struct modules.
diff --git a/Modules/structmodule.c b/Modules/structmodule.c
index 2210c33..e4e1eb5 100644
--- a/Modules/structmodule.c
+++ b/Modules/structmodule.c
@@ -185,301 +185,27 @@
/* Floating point helpers */
-/* These use ANSI/IEEE Standard 754-1985 (Standard for Binary Floating
- Point Arithmetic). See the following URL:
- http://www.psc.edu/general/software/packages/ieee/ieee.html */
-
-/* XXX Inf/NaN are not handled quite right (but underflow is!) */
-
-static int
-pack_float(double x, /* The number to pack */
- char *p, /* Where to pack the high order byte */
- int incr) /* 1 for big-endian; -1 for little-endian */
-{
- int s;
- int e;
- double f;
- long fbits;
-
- if (x < 0) {
- s = 1;
- x = -x;
- }
- else
- s = 0;
-
- f = frexp(x, &e);
-
- /* Normalize f to be in the range [1.0, 2.0) */
- if (0.5 <= f && f < 1.0) {
- f *= 2.0;
- e--;
- }
- else if (f == 0.0) {
- e = 0;
- }
- else {
- PyErr_SetString(PyExc_SystemError,
- "frexp() result out of range");
- return -1;
- }
-
- if (e >= 128)
- goto Overflow;
- else if (e < -126) {
- /* Gradual underflow */
- f = ldexp(f, 126 + e);
- e = 0;
- }
- else if (!(e == 0 && f == 0.0)) {
- e += 127;
- f -= 1.0; /* Get rid of leading 1 */
- }
-
- f *= 8388608.0; /* 2**23 */
- fbits = (long) floor(f + 0.5); /* Round */
- assert(fbits <= 8388608);
- if (fbits >> 23) {
- /* The carry propagated out of a string of 23 1 bits. */
- fbits = 0;
- ++e;
- if (e >= 255)
- goto Overflow;
- }
-
- /* First byte */
- *p = (s<<7) | (e>>1);
- p += incr;
-
- /* Second byte */
- *p = (char) (((e&1)<<7) | (fbits>>16));
- p += incr;
-
- /* Third byte */
- *p = (fbits>>8) & 0xFF;
- p += incr;
-
- /* Fourth byte */
- *p = fbits&0xFF;
-
- /* Done */
- return 0;
-
- Overflow:
- PyErr_SetString(PyExc_OverflowError,
- "float too large to pack with f format");
- return -1;
-}
-
-static int
-pack_double(double x, /* The number to pack */
- char *p, /* Where to pack the high order byte */
- int incr) /* 1 for big-endian; -1 for little-endian */
-{
- int s;
- int e;
- double f;
- long fhi, flo;
-
- if (x < 0) {
- s = 1;
- x = -x;
- }
- else
- s = 0;
-
- f = frexp(x, &e);
-
- /* Normalize f to be in the range [1.0, 2.0) */
- if (0.5 <= f && f < 1.0) {
- f *= 2.0;
- e--;
- }
- else if (f == 0.0) {
- e = 0;
- }
- else {
- PyErr_SetString(PyExc_SystemError,
- "frexp() result out of range");
- return -1;
- }
-
- if (e >= 1024)
- goto Overflow;
- else if (e < -1022) {
- /* Gradual underflow */
- f = ldexp(f, 1022 + e);
- e = 0;
- }
- else if (!(e == 0 && f == 0.0)) {
- e += 1023;
- f -= 1.0; /* Get rid of leading 1 */
- }
-
- /* fhi receives the high 28 bits; flo the low 24 bits (== 52 bits) */
- f *= 268435456.0; /* 2**28 */
- fhi = (long) floor(f); /* Truncate */
- assert(fhi < 268435456);
-
- f -= (double)fhi;
- f *= 16777216.0; /* 2**24 */
- flo = (long) floor(f + 0.5); /* Round */
- assert(flo <= 16777216);
- if (flo >> 24) {
- /* The carry propagated out of a string of 24 1 bits. */
- flo = 0;
- ++fhi;
- if (fhi >> 28) {
- /* And it also progagated out of the next 28 bits. */
- fhi = 0;
- ++e;
- if (e >= 2047)
- goto Overflow;
- }
- }
-
- /* First byte */
- *p = (s<<7) | (e>>4);
- p += incr;
-
- /* Second byte */
- *p = (char) (((e&0xF)<<4) | (fhi>>24));
- p += incr;
-
- /* Third byte */
- *p = (fhi>>16) & 0xFF;
- p += incr;
-
- /* Fourth byte */
- *p = (fhi>>8) & 0xFF;
- p += incr;
-
- /* Fifth byte */
- *p = fhi & 0xFF;
- p += incr;
-
- /* Sixth byte */
- *p = (flo>>16) & 0xFF;
- p += incr;
-
- /* Seventh byte */
- *p = (flo>>8) & 0xFF;
- p += incr;
-
- /* Eighth byte */
- *p = flo & 0xFF;
- p += incr;
-
- /* Done */
- return 0;
-
- Overflow:
- PyErr_SetString(PyExc_OverflowError,
- "float too large to pack with d format");
- return -1;
-}
-
static PyObject *
-unpack_float(const char *p, /* Where the high order byte is */
- int incr) /* 1 for big-endian; -1 for little-endian */
+unpack_float(const char *p, /* start of 4-byte string */
+ int le) /* true for little-endian, false for big-endian */
{
- int s;
- int e;
- long f;
double x;
- /* First byte */
- s = (*p>>7) & 1;
- e = (*p & 0x7F) << 1;
- p += incr;
-
- /* Second byte */
- e |= (*p>>7) & 1;
- f = (*p & 0x7F) << 16;
- p += incr;
-
- /* Third byte */
- f |= (*p & 0xFF) << 8;
- p += incr;
-
- /* Fourth byte */
- f |= *p & 0xFF;
-
- x = (double)f / 8388608.0;
-
- /* XXX This sadly ignores Inf/NaN issues */
- if (e == 0)
- e = -126;
- else {
- x += 1.0;
- e -= 127;
- }
- x = ldexp(x, e);
-
- if (s)
- x = -x;
-
+ x = _PyFloat_Unpack4((unsigned char *)p, le);
+ if (x == -1.0 && PyErr_Occurred())
+ return NULL;
return PyFloat_FromDouble(x);
}
static PyObject *
-unpack_double(const char *p, /* Where the high order byte is */
- int incr) /* 1 for big-endian; -1 for little-endian */
+unpack_double(const char *p, /* start of 8-byte string */
+ int le) /* true for little-endian, false for big-endian */
{
- int s;
- int e;
- long fhi, flo;
double x;
- /* First byte */
- s = (*p>>7) & 1;
- e = (*p & 0x7F) << 4;
- p += incr;
-
- /* Second byte */
- e |= (*p>>4) & 0xF;
- fhi = (*p & 0xF) << 24;
- p += incr;
-
- /* Third byte */
- fhi |= (*p & 0xFF) << 16;
- p += incr;
-
- /* Fourth byte */
- fhi |= (*p & 0xFF) << 8;
- p += incr;
-
- /* Fifth byte */
- fhi |= *p & 0xFF;
- p += incr;
-
- /* Sixth byte */
- flo = (*p & 0xFF) << 16;
- p += incr;
-
- /* Seventh byte */
- flo |= (*p & 0xFF) << 8;
- p += incr;
-
- /* Eighth byte */
- flo |= *p & 0xFF;
- p += incr;
-
- x = (double)fhi + (double)flo / 16777216.0; /* 2**24 */
- x /= 268435456.0; /* 2**28 */
-
- /* XXX This sadly ignores Inf/NaN */
- if (e == 0)
- e = -1022;
- else {
- x += 1.0;
- e -= 1023;
- }
- x = ldexp(x, e);
-
- if (s)
- x = -x;
-
+ x = _PyFloat_Unpack8((unsigned char *)p, le);
+ if (x == -1.0 && PyErr_Occurred())
+ return NULL;
return PyFloat_FromDouble(x);
}
@@ -887,13 +613,13 @@
static PyObject *
bu_float(const char *p, const formatdef *f)
{
- return unpack_float(p, 1);
+ return unpack_float(p, 0);
}
static PyObject *
bu_double(const char *p, const formatdef *f)
{
- return unpack_double(p, 1);
+ return unpack_double(p, 0);
}
static int
@@ -967,7 +693,7 @@
"required argument is not a float");
return -1;
}
- return pack_float(x, p, 1);
+ return _PyFloat_Pack4(x, (unsigned char *)p, 0);
}
static int
@@ -979,7 +705,7 @@
"required argument is not a float");
return -1;
}
- return pack_double(x, p, 1);
+ return _PyFloat_Pack8(x, (unsigned char *)p, 0);
}
static formatdef bigendian_table[] = {
@@ -1053,13 +779,13 @@
static PyObject *
lu_float(const char *p, const formatdef *f)
{
- return unpack_float(p+3, -1);
+ return unpack_float(p, 1);
}
static PyObject *
lu_double(const char *p, const formatdef *f)
{
- return unpack_double(p+7, -1);
+ return unpack_double(p, 1);
}
static int
@@ -1133,7 +859,7 @@
"required argument is not a float");
return -1;
}
- return pack_float(x, p+3, -1);
+ return _PyFloat_Pack4(x, (unsigned char *)p, 1);
}
static int
@@ -1145,7 +871,7 @@
"required argument is not a float");
return -1;
}
- return pack_double(x, p+7, -1);
+ return _PyFloat_Pack8(x, (unsigned char *)p, 1);
}
static formatdef lilendian_table[] = {