extmod/modurandom: Add some extra random functions.

Functions added are:
- randint
- randrange
- choice
- random
- uniform

They are enabled with configuration variable
MICROPY_PY_URANDOM_EXTRA_FUNCS, which is disabled by default.  It is
enabled for unix coverage build and stmhal.

5 files changed, 144 insertions, 1 deletions

diff --git a/extmod/modurandom.c b/extmod/modurandom.c
index 3ed6e9130e..27d7177207 100644
--- a/extmod/modurandom.c
+++ b/extmod/modurandom.c
@@ -53,6 +53,24 @@ STATIC uint32_t yasmarang(void)
 
 // End of Yasmarang
 
+#if MICROPY_PY_URANDOM_EXTRA_FUNCS
+
+// returns an unsigned integer below the given argument
+// n must not be zero
+STATIC uint32_t yasmarang_randbelow(uint32_t n) {
+    uint32_t mask = 1;
+    while ((n & mask) < n) {
+        mask = (mask << 1) | 1;
+    }
+    uint32_t r;
+    do {
+        r = yasmarang() & mask;
+    } while (r >= n);
+    return r;
+}
+
+#endif
+
 STATIC mp_obj_t mod_urandom_getrandbits(mp_obj_t num_in) {
     int n = mp_obj_get_int(num_in);
     if (n > 32 || n == 0) {
@@ -75,10 +93,122 @@ STATIC mp_obj_t mod_urandom_seed(mp_obj_t seed_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_seed_obj, mod_urandom_seed);
 
+#if MICROPY_PY_URANDOM_EXTRA_FUNCS
+
+STATIC mp_obj_t mod_urandom_randrange(size_t n_args, const mp_obj_t *args) {
+    mp_int_t start = mp_obj_get_int(args[0]);
+    if (n_args == 1) {
+        // range(stop)
+        if (start > 0) {
+            return mp_obj_new_int(yasmarang_randbelow(start));
+        } else {
+            nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
+        }
+    } else {
+        mp_int_t stop = mp_obj_get_int(args[1]);
+        if (n_args == 2) {
+            // range(start, stop)
+            if (start < stop) {
+                return mp_obj_new_int(start + yasmarang_randbelow(stop - start));
+            } else {
+                nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
+            }
+        } else {
+            // range(start, stop, step)
+            mp_int_t step = mp_obj_get_int(args[2]);
+            mp_int_t n;
+            if (step > 0) {
+                n = (stop - start + step - 1) / step;
+            } else if (step < 0) {
+                n = (stop - start + step + 1) / step;
+            } else {
+                nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
+            }
+            if (n > 0) {
+                return mp_obj_new_int(start + step * yasmarang_randbelow(n));
+            } else {
+                nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
+            }
+        }
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_urandom_randrange_obj, 1, 3, mod_urandom_randrange);
+
+STATIC mp_obj_t mod_urandom_randint(mp_obj_t a_in, mp_obj_t b_in) {
+    mp_int_t a = mp_obj_get_int(a_in);
+    mp_int_t b = mp_obj_get_int(b_in);
+    if (a <= b) {
+        return mp_obj_new_int(a + yasmarang_randbelow(b - a + 1));
+    } else {
+        nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_randint_obj, mod_urandom_randint);
+
+STATIC mp_obj_t mod_urandom_choice(mp_obj_t seq) {
+    mp_int_t len = mp_obj_get_int(mp_obj_len(seq));
+    if (len > 0) {
+        return mp_obj_subscr(seq, mp_obj_new_int(yasmarang_randbelow(len)), MP_OBJ_SENTINEL);
+    } else {
+        nlr_raise(mp_obj_new_exception(&mp_type_IndexError));
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_choice_obj, mod_urandom_choice);
+
+#if MICROPY_PY_BUILTINS_FLOAT
+
+// returns a number in the range [0..1) using Yasmarang to fill in the fraction bits
+STATIC mp_float_t yasmarang_float(void) {
+    #if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+    typedef uint64_t mp_float_int_t;
+    #elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+    typedef uint32_t mp_float_int_t;
+    #endif
+    union {
+        mp_float_t f;
+        #if MP_ENDIANNESS_LITTLE
+        struct { mp_float_int_t frc:MP_FLOAT_FRAC_BITS, exp:MP_FLOAT_EXP_BITS, sgn:1; } p;
+        #else
+        struct { mp_float_int_t sgn:1, exp:MP_FLOAT_EXP_BITS, frc:MP_FLOAT_FRAC_BITS; } p;
+        #endif
+    } u;
+    u.p.sgn = 0;
+    u.p.exp = (1 << (MP_FLOAT_EXP_BITS - 1)) - 1;
+    if (MP_FLOAT_FRAC_BITS <= 32) {
+        u.p.frc = yasmarang();
+    } else {
+        u.p.frc = ((uint64_t)yasmarang() << 32) | (uint64_t)yasmarang();
+    }
+    return u.f - 1;
+}
+
+STATIC mp_obj_t mod_urandom_random(void) {
+    return mp_obj_new_float(yasmarang_float());
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_urandom_random_obj, mod_urandom_random);
+
+STATIC mp_obj_t mod_urandom_uniform(mp_obj_t a_in, mp_obj_t b_in) {
+    mp_float_t a = mp_obj_get_float(a_in);
+    mp_float_t b = mp_obj_get_float(b_in);
+    return mp_obj_new_float(a + (b - a) * yasmarang_float());
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_uniform_obj, mod_urandom_uniform);
+
+#endif
+
+#endif // MICROPY_PY_URANDOM_EXTRA_FUNCS
+
 STATIC const mp_rom_map_elem_t mp_module_urandom_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_urandom) },
     { MP_ROM_QSTR(MP_QSTR_getrandbits), MP_ROM_PTR(&mod_urandom_getrandbits_obj) },
     { MP_ROM_QSTR(MP_QSTR_seed), MP_ROM_PTR(&mod_urandom_seed_obj) },
+    #if MICROPY_PY_URANDOM_EXTRA_FUNCS
+    { MP_ROM_QSTR(MP_QSTR_randrange), MP_ROM_PTR(&mod_urandom_randrange_obj) },
+    { MP_ROM_QSTR(MP_QSTR_randint), MP_ROM_PTR(&mod_urandom_randint_obj) },
+    { MP_ROM_QSTR(MP_QSTR_choice), MP_ROM_PTR(&mod_urandom_choice_obj) },
+    { MP_ROM_QSTR(MP_QSTR_random), MP_ROM_PTR(&mod_urandom_random_obj) },
+    { MP_ROM_QSTR(MP_QSTR_uniform), MP_ROM_PTR(&mod_urandom_uniform_obj) },
+    #endif
 };
 
 STATIC MP_DEFINE_CONST_DICT(mp_module_urandom_globals, mp_module_urandom_globals_table);
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 72af343ddf..402e97acc2 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -787,6 +787,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_URANDOM (0)
 #endif
 
+// Whether to include: randrange, randint, choice, random, uniform
+#ifndef MICROPY_PY_URANDOM_EXTRA_FUNCS
+#define MICROPY_PY_URANDOM_EXTRA_FUNCS (0)
+#endif
+
 #ifndef MICROPY_PY_MACHINE
 #define MICROPY_PY_MACHINE (0)
 #endif
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index dd76c3d43b..122fca128b 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -686,4 +686,11 @@ Q(dupterm)
 Q(urandom)
 Q(getrandbits)
 Q(seed)
+#if MICROPY_PY_URANDOM_EXTRA_FUNCS
+Q(randrange)
+Q(randint)
+Q(choice)
+Q(random)
+Q(uniform)
+#endif
 #endif
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index 47ad0a4156..eaf1da716d 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -80,6 +80,7 @@
 #define MICROPY_PY_IO_FILEIO        (1)
 #define MICROPY_PY_UBINASCII        (1)
 #define MICROPY_PY_URANDOM          (1)
+#define MICROPY_PY_URANDOM_EXTRA_FUNCS (1)
 #define MICROPY_PY_UCTYPES          (1)
 #define MICROPY_PY_UZLIB            (1)
 #define MICROPY_PY_UJSON            (1)
diff --git a/unix/Makefile b/unix/Makefile
index 7508a04bee..39e671f9de 100644
--- a/unix/Makefile
+++ b/unix/Makefile
@@ -193,7 +193,7 @@ freedos:
 
 # build an interpreter for coverage testing and do the testing
 coverage:
-	$(MAKE) COPT="-O0" CFLAGS_EXTRA='-fprofile-arcs -ftest-coverage -Wdouble-promotion -Wformat -Wmissing-declarations -Wmissing-prototypes -Wold-style-definition -Wpointer-arith -Wshadow -Wsign-compare -Wuninitialized -Wunused-parameter -DMICROPY_UNIX_COVERAGE' LDFLAGS_EXTRA='-fprofile-arcs -ftest-coverage' BUILD=build-coverage PROG=micropython_coverage
+	$(MAKE) COPT="-O0" CFLAGS_EXTRA='-fprofile-arcs -ftest-coverage -Wdouble-promotion -Wformat -Wmissing-declarations -Wmissing-prototypes -Wold-style-definition -Wpointer-arith -Wshadow -Wsign-compare -Wuninitialized -Wunused-parameter -DMICROPY_UNIX_COVERAGE -DMICROPY_PY_URANDOM_EXTRA_FUNCS' LDFLAGS_EXTRA='-fprofile-arcs -ftest-coverage' BUILD=build-coverage PROG=micropython_coverage
 
 coverage_test: coverage
 	$(eval DIRNAME=$(notdir $(CURDIR)))