rand: update module

vlib/rand/rand.v

@@ -1,8 +1,13 @@
 // Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
 // Use of this source code is governed by an MIT license
 // that can be found in the LICENSE file.
+
 module rand
 
+fn C.rand() int
+
+fn C.srand(u32)
+
 pub fn seed(s int) {
 	C.srand(s)
 }
@@ -11,24 +16,10 @@ pub fn next(max int) int {
 	return C.rand() % max
 }
 
-fn C.rand() int
-/**
- * rand_r - reentrant pseudo-random number generator
- *
- * @param seed byref reentrant seed, holding current state
- *
- * @return a value between 0 and C.RAND_MAX (inclusive)
- */
-
-
-
-pub fn rand_r(seed &int) int {
-	unsafe{
-		mut rs := seed
-		ns := (*rs * 1103515245 + 12345)
-		*rs = ns
-		return ns & 0x7fffffff
-	}
+// rand_r returns a pseudo-random number;
+// writes a result value to the seed argument.
+pub fn rand_r(seed mut int) int {
+	ns := *seed * 1103515245 + 12345
+	(*seed) = ns
+	return ns & 0x7fffffff
 }
-
-

vlib/rand/rand_test.v

@@ -1,58 +1,58 @@
 import rand
 
+const (
+	rnd_count = 20
+	seeds = [42, 256]
+)
+
+fn test_rand_reproducibility() {
+	for seed in seeds {
+		mut randoms1 := gen_randoms(seed)
+		mut randoms2 := gen_randoms(seed)
+
+		assert_randoms_equal(randoms1, randoms2)
+	}
+}
+
+fn test_rand_r_reproducibility() {
+	for seed in seeds {
+		mut randoms1 := gen_randoms_r(seed)
+		mut randoms2 := gen_randoms_r(seed)
+
+		assert_randoms_equal(randoms1, randoms2)
+	}
+}
+
+fn test_rand_r_seed_update() {
+	seed := 10
+
+	for _ in 0..rnd_count {
+		prev_seed := seed
+		res := rand.rand_r(&seed)
+
+		assert prev_seed != seed
+	}
+}
+
 fn gen_randoms(seed int) []int {
-	mut randoms := [0].repeat(20)
+	mut randoms := [0].repeat(rnd_count)
 	rand.seed(seed)
-	for i in 0..20 {
+	for i in 0..rnd_count {
 		randoms[i] = rand.next(100)
 	}
 	return randoms
 }
 
-fn test_rand_reproducibility() {
-	mut randoms1 := gen_randoms(42)
-	mut randoms2 := gen_randoms(42)
-	assert randoms1.len == randoms2.len
-
-	mut len := randoms1.len
-	for i in 0..len {
-		assert randoms1[i] == randoms2[i]
-	}
-
-	randoms1 = gen_randoms(256)
-	randoms2 = gen_randoms(256)
-	assert randoms1.len == randoms2.len
-
-	len = randoms1.len
-	for i in 0..len {
-		assert randoms1[i] == randoms2[i]
-	}
-}
-
 fn gen_randoms_r(seed int) []int {
-	mut randoms := [0].repeat(20)
-	for i in 0..20 {
+	mut randoms := [0].repeat(rnd_count)
+	for i in 0..rnd_count {
 		randoms[i] = rand.rand_r(&seed)
 	}
 	return randoms
 }
 
-fn test_rand_r_reproducibility() {
-	mut randoms1 := gen_randoms_r(42)
-	mut randoms2 := gen_randoms_r(42)
-	assert randoms1.len == randoms2.len
-
-	mut len := randoms1.len
-	for i in 0..len {
-		assert randoms1[i] == randoms2[i]
-	}
-
-	randoms1 = gen_randoms_r(256)
-	randoms2 = gen_randoms_r(256)
-	assert randoms1.len == randoms2.len
-
-	len = randoms1.len
-	for i in 0..len {
-		assert randoms1[i] == randoms2[i]
+fn assert_randoms_equal(r1, r2 []int) {
+	for i in 0..rnd_count {
+		assert r1[i] == r2[i]
 	}
 }