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py/obj: Fix nan handling in object REPR_C and REPR_D.

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CPython math.nan is positive with regards to copysign.  The signaling bit
(aka sign flag) was incorrectly set.

In addition, REPR_C and REPR_D should only use the _true_ nan to prevent
system crash in case of hand-crafted floats.  For instance, with REPR_C,
any nan-like float following the pattern
`01111111 1xxxxxxx xxxxxxxx xxxxx1xx` would be switched to an immediate
object or a qstr string.  When the qstr index is too large, this would
cause a crash.

This commit fixes the issue, and adds the relevant test cases.

Signed-off-by: Yoctopuce dev <dev@yoctopuce.com>
This commit is contained in:
Yoctopuce dev 2025-06-19 15:47:13 +02:00 committed by Damien George
parent 66c0148022
commit e57aa7e70a
5 changed files with 37 additions and 4 deletions
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5
ports/windows/mpconfigport.h
View file

@ -266,6 +266,11 @@ typedef long mp_off_t;
#endif
#endif
// VC++ 2017 fixes
#if (_MSC_VER < 1920)
#define MICROPY_PY_MATH_COPYSIGN_FIX_NAN (1)
#endif
// CL specific definitions
#ifndef __cplusplus

5
py/modmath.c
View file

@ -161,6 +161,11 @@ MATH_FUN_2(atan2, atan2)
MATH_FUN_1_TO_INT(ceil, ceil)
// copysign(x, y)
static mp_float_t MICROPY_FLOAT_C_FUN(copysign_func)(mp_float_t x, mp_float_t y) {
#if MICROPY_PY_MATH_COPYSIGN_FIX_NAN
if (isnan(y)) {
y = 0.0;
}
#endif
return MICROPY_FLOAT_C_FUN(copysign)(x, y);
}
MATH_FUN_2(copysign, copysign_func)

20
py/obj.h
View file

@ -184,13 +184,15 @@ static inline bool mp_obj_is_small_int(mp_const_obj_t o) {
#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 1) | 1))
#if MICROPY_PY_BUILTINS_FLOAT
#define MP_OBJ_NEW_CONST_FLOAT(f) MP_ROM_PTR((mp_obj_t)((((((uint64_t)f) & ~3) | 2) + 0x80800000) & 0xffffffff))
#include <math.h>
// note: MP_OBJ_NEW_CONST_FLOAT should be a MP_ROM_PTR but that macro isn't available yet
#define MP_OBJ_NEW_CONST_FLOAT(f) ((mp_obj_t)((((((uint64_t)f) & ~3) | 2) + 0x80800000) & 0xffffffff))
#define mp_const_float_e MP_OBJ_NEW_CONST_FLOAT(0x402df854)
#define mp_const_float_pi MP_OBJ_NEW_CONST_FLOAT(0x40490fdb)
#define mp_const_float_nan MP_OBJ_NEW_CONST_FLOAT(0x7fc00000)
#if MICROPY_PY_MATH_CONSTANTS
#define mp_const_float_tau MP_OBJ_NEW_CONST_FLOAT(0x40c90fdb)
#define mp_const_float_inf MP_OBJ_NEW_CONST_FLOAT(0x7f800000)
#define mp_const_float_nan MP_OBJ_NEW_CONST_FLOAT(0xffc00000)
#endif
static inline bool mp_obj_is_float(mp_const_obj_t o) {
@ -207,6 +209,10 @@ static inline mp_float_t mp_obj_float_get(mp_const_obj_t o) {
return num.f;
}
static inline mp_obj_t mp_obj_new_float(mp_float_t f) {
if (isnan(f)) {
// prevent creation of bad nanboxed pointers via array.array or struct
return mp_const_float_nan;
}
union {
mp_float_t f;
mp_uint_t u;
@ -257,12 +263,13 @@ static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o) {
#error MICROPY_OBJ_REPR_D requires MICROPY_FLOAT_IMPL_DOUBLE
#endif
#include <math.h>
#define mp_const_float_e {((mp_obj_t)((uint64_t)0x4005bf0a8b145769 + 0x8004000000000000))}
#define mp_const_float_pi {((mp_obj_t)((uint64_t)0x400921fb54442d18 + 0x8004000000000000))}
#define mp_const_float_nan {((mp_obj_t)((uint64_t)0x7ff8000000000000 + 0x8004000000000000))}
#if MICROPY_PY_MATH_CONSTANTS
#define mp_const_float_tau {((mp_obj_t)((uint64_t)0x401921fb54442d18 + 0x8004000000000000))}
#define mp_const_float_inf {((mp_obj_t)((uint64_t)0x7ff0000000000000 + 0x8004000000000000))}
#define mp_const_float_nan {((mp_obj_t)((uint64_t)0xfff8000000000000 + 0x8004000000000000))}
#endif
static inline bool mp_obj_is_float(mp_const_obj_t o) {
@ -276,6 +283,13 @@ static inline mp_float_t mp_obj_float_get(mp_const_obj_t o) {
return num.f;
}
static inline mp_obj_t mp_obj_new_float(mp_float_t f) {
if (isnan(f)) {
// prevent creation of bad nanboxed pointers via array.array or struct
struct {
uint64_t r;
} num = mp_const_float_nan;
return num.r;
}
union {
mp_float_t f;
uint64_t r;

8
tests/float/float_array.py
View file

@ -19,4 +19,10 @@ def test(a):
test(array("f"))
test(array("d"))
print("{:.4f}".format(array("f", bytes(array("I", [0x3DCCCCCC])))[0]))
# hand-crafted floats, including non-standard nan
for float_hex in (0x3DCCCCCC, 0x7F800024, 0x7FC00004):
f = array("f", bytes(array("I", [float_hex])))[0]
if type(f) is float:
print("{:.4e}".format(f))
else:
print(f)

3
tests/float/math_constants_extra.py
View file

@ -9,9 +9,12 @@ except (ImportError, AttributeError):
raise SystemExit
print(math.tau == 2.0 * math.pi)
print(math.copysign(1.0, math.tau))
print(math.inf == float("inf"))
print(-math.inf == -float("inf"))
print(math.copysign(1.0, math.inf))
print(isnan(math.nan))
print(isnan(-math.nan))
print(math.copysign(1.0, math.nan))