py/modmath: Add math.tau, math.nan and math.inf constants.

Configurable by the new MICROPY_PY_MATH_CONSTANTS option.

ports/unix/variants/coverage/mpconfigvariant.h

@@ -48,6 +48,7 @@
 #define MICROPY_PY_BUILTINS_HELP       (1)
 #define MICROPY_PY_BUILTINS_HELP_MODULES (1)
 #define MICROPY_PY_SYS_GETSIZEOF       (1)
+#define MICROPY_PY_MATH_CONSTANTS      (1)
 #define MICROPY_PY_MATH_FACTORIAL      (1)
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS (1)
 #define MICROPY_PY_IO_BUFFEREDWRITER (1)

ports/unix/variants/dev/mpconfigvariant.h

@@ -33,6 +33,7 @@
 
 #define MICROPY_PY_BUILTINS_HELP                (1)
 #define MICROPY_PY_BUILTINS_HELP_MODULES        (1)
+#define MICROPY_PY_MATH_CONSTANTS               (1)
 #define MICROPY_PY_SYS_SETTRACE                 (1)
 #define MICROPY_PY_UOS_VFS                      (1)
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS          (1)

ports/windows/variants/dev/mpconfigvariant.h

@@ -30,6 +30,7 @@
 
 #define MICROPY_PY_BUILTINS_HELP                (1)
 #define MICROPY_PY_BUILTINS_HELP_MODULES        (1)
+#define MICROPY_PY_MATH_CONSTANTS               (1)
 #define MICROPY_PY_SYS_SETTRACE                 (1)
 #define MICROPY_PERSISTENT_CODE_SAVE            (1)
 #define MICROPY_COMP_CONST                      (0)

py/modmath.c

@@ -371,6 +371,11 @@ STATIC const mp_rom_map_elem_t mp_module_math_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_math) },
     { MP_ROM_QSTR(MP_QSTR_e), mp_const_float_e },
     { MP_ROM_QSTR(MP_QSTR_pi), mp_const_float_pi },
+    #if MICROPY_PY_MATH_CONSTANTS
+    { MP_ROM_QSTR(MP_QSTR_tau), mp_const_float_tau },
+    { MP_ROM_QSTR(MP_QSTR_inf), mp_const_float_inf },
+    { MP_ROM_QSTR(MP_QSTR_nan), mp_const_float_nan },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_sqrt), MP_ROM_PTR(&mp_math_sqrt_obj) },
     { MP_ROM_QSTR(MP_QSTR_pow), MP_ROM_PTR(&mp_math_pow_obj) },
     { MP_ROM_QSTR(MP_QSTR_exp), MP_ROM_PTR(&mp_math_exp_obj) },

py/mpconfig.h

@@ -1221,6 +1221,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_MATH (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
 #endif
 
+// Whether to provide all math module constants (Python 3.5+), or just pi and e.
+#ifndef MICROPY_PY_MATH_CONSTANTS
+#define MICROPY_PY_MATH_CONSTANTS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
+#endif
+
 // Whether to provide special math functions: math.{erf,erfc,gamma,lgamma}
 #ifndef MICROPY_PY_MATH_SPECIAL_FUNCTIONS
 #define MICROPY_PY_MATH_SPECIAL_FUNCTIONS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)

py/obj.h

@@ -104,8 +104,18 @@ static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o) {
 #if MICROPY_PY_BUILTINS_FLOAT
 #define mp_const_float_e MP_ROM_PTR(&mp_const_float_e_obj)
 #define mp_const_float_pi MP_ROM_PTR(&mp_const_float_pi_obj)
+#if MICROPY_PY_MATH_CONSTANTS
+#define mp_const_float_tau MP_ROM_PTR(&mp_const_float_tau_obj)
+#define mp_const_float_inf MP_ROM_PTR(&mp_const_float_inf_obj)
+#define mp_const_float_nan MP_ROM_PTR(&mp_const_float_nan_obj)
+#endif
 extern const struct _mp_obj_float_t mp_const_float_e_obj;
 extern const struct _mp_obj_float_t mp_const_float_pi_obj;
+#if MICROPY_PY_MATH_CONSTANTS
+extern const struct _mp_obj_float_t mp_const_float_tau_obj;
+extern const struct _mp_obj_float_t mp_const_float_inf_obj;
+extern const struct _mp_obj_float_t mp_const_float_nan_obj;
+#endif
 
 #define mp_obj_is_float(o) mp_obj_is_type((o), &mp_type_float)
 mp_float_t mp_obj_float_get(mp_obj_t self_in);
@@ -139,8 +149,18 @@ static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o) {
 #if MICROPY_PY_BUILTINS_FLOAT
 #define mp_const_float_e MP_ROM_PTR(&mp_const_float_e_obj)
 #define mp_const_float_pi MP_ROM_PTR(&mp_const_float_pi_obj)
+#if MICROPY_PY_MATH_CONSTANTS
+#define mp_const_float_tau MP_ROM_PTR(&mp_const_float_tau_obj)
+#define mp_const_float_inf MP_ROM_PTR(&mp_const_float_inf_obj)
+#define mp_const_float_nan MP_ROM_PTR(&mp_const_float_nan_obj)
+#endif
 extern const struct _mp_obj_float_t mp_const_float_e_obj;
 extern const struct _mp_obj_float_t mp_const_float_pi_obj;
+#if MICROPY_PY_MATH_CONSTANTS
+extern const struct _mp_obj_float_t mp_const_float_tau_obj;
+extern const struct _mp_obj_float_t mp_const_float_inf_obj;
+extern const struct _mp_obj_float_t mp_const_float_nan_obj;
+#endif
 
 #define mp_obj_is_float(o) mp_obj_is_type((o), &mp_type_float)
 mp_float_t mp_obj_float_get(mp_obj_t self_in);
@@ -162,6 +182,11 @@ static inline bool mp_obj_is_small_int(mp_const_obj_t o) {
 #if MICROPY_PY_BUILTINS_FLOAT
 #define mp_const_float_e MP_ROM_PTR((mp_obj_t)(((0x402df854 & ~3) | 2) + 0x80800000))
 #define mp_const_float_pi MP_ROM_PTR((mp_obj_t)(((0x40490fdb & ~3) | 2) + 0x80800000))
+#if MICROPY_PY_MATH_CONSTANTS
+#define mp_const_float_tau MP_ROM_PTR((mp_obj_t)(((0x40c90fdb & ~3) | 2) + 0x80800000))
+#define mp_const_float_inf MP_ROM_PTR((mp_obj_t)(((0x7f800000 & ~3) | 2) + 0x80800000))
+#define mp_const_float_nan MP_ROM_PTR((mp_obj_t)(((0xffc00000 & ~3) | 2) + 0x80800000))
+#endif
 
 static inline bool mp_obj_is_float(mp_const_obj_t o) {
     return (((mp_uint_t)(o)) & 3) == 2 && (((mp_uint_t)(o)) & 0xff800007) != 0x00000006;
@@ -226,6 +251,11 @@ static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o) {
 
 #define mp_const_float_e {((mp_obj_t)((uint64_t)0x4005bf0a8b145769 + 0x8004000000000000))}
 #define mp_const_float_pi {((mp_obj_t)((uint64_t)0x400921fb54442d18 + 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) {
     return ((uint64_t)(o) & 0xfffc000000000000) != 0;

py/objfloat.c

@@ -54,6 +54,14 @@ typedef struct _mp_obj_float_t {
 
 const mp_obj_float_t mp_const_float_e_obj = {{&mp_type_float}, (mp_float_t)M_E};
 const mp_obj_float_t mp_const_float_pi_obj = {{&mp_type_float}, (mp_float_t)M_PI};
+#if MICROPY_PY_MATH_CONSTANTS
+#ifndef NAN
+#error NAN macro is not defined
+#endif
+const mp_obj_float_t mp_const_float_tau_obj = {{&mp_type_float}, (mp_float_t)(2.0 * M_PI)};
+const mp_obj_float_t mp_const_float_inf_obj = {{&mp_type_float}, (mp_float_t)INFINITY};
+const mp_obj_float_t mp_const_float_nan_obj = {{&mp_type_float}, (mp_float_t)NAN};
+#endif
 
 #endif
 

tests/float/math_constants.py

@@ -0,0 +1,11 @@
+# Tests various constants of the math module.
+try:
+    import math
+    from math import exp, cos
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+print(math.e == exp(1.0))
+
+print(cos(math.pi))

tests/float/math_constants_extra.py

@@ -0,0 +1,17 @@
+# Tests constants of the math module available only with MICROPY_PY_MATH_CONSTANTS.
+try:
+    import math
+    from math import isnan
+
+    math.tau
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+print(math.tau == 2.0 * math.pi)
+
+print(math.inf == float("inf"))
+print(-math.inf == -float("inf"))
+
+print(isnan(math.nan))
+print(isnan(-math.nan))