Merge branch 'rand' of github.com:coolwanglu/emscripten into incoming

2 files changed, 58 insertions, 45 deletions

diff --git a/src/library.js b/src/library.js
index 4c0f790f..64da5444 100644
--- a/src/library.js
+++ b/src/library.js
@@ -3447,13 +3447,31 @@ LibraryManager.library = {
     return limit;
   },
 
-  // Use browser's Math.random(). We can't set a seed, though.
-  srand: function(seed) {}, // XXX ignored
+  __rand_seed: 'allocate([0x0273459b, 0, 0, 0], "i32", ALLOC_STATIC)',
+  srand__deps: ['__rand_seed'],
+  srand: function(seed) {
+    {{{ makeSetValue('___rand_seed', 0, 'seed', 'i32') }}}
+  }, 
+  rand_r__deps: ['__rand_seed'],
+  rand_r: function(seedp) { 
+    var val = {{{ makeGetValue('seedp', 0, 'i32') }}};
+    // calculate val * 31010991 + 0x676e6177
+    // i32 multiplication will be rounded by javascript
+    var valh = val >> 16;
+    var vall = val & 0xffff;
+
+    var c = 31010991;
+    var ch = c >> 16;
+    var cl = c & 0xffff;
+
+    val = (((valh * cl + vall * ch) << 16) + vall * cl + 0x676e6177) & 0x7fffffff;
+
+    {{{ makeSetValue('seedp', 0, 'val', 'i32') }}}
+    return val;
+  },
+  rand__deps: ['rand_r'],
   rand: function() {
-    return Math.floor(Math.random()*0x80000000);
-  },
-  rand_r: function(seed) { // XXX ignores the seed
-    return Math.floor(Math.random()*0x80000000);
+    return _rand_r(___rand_seed);
   },
 
   drand48: function() {
diff --git a/tests/test_core.py b/tests/test_core.py
index 6c2968f6..aa69bc4e 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -3550,48 +3550,43 @@ ok
 ''', post_build=self.dlfcn_post_build)
 
   def test_rand(self):
-    return self.skip('rand() is now random') # FIXME
-
-    src = r'''
-      #include <stdio.h>
-      #include <stdlib.h>
-
-      int main() {
-        printf("%d\n", rand());
-        printf("%d\n", rand());
-
-        srand(123);
-        printf("%d\n", rand());
-        printf("%d\n", rand());
-        srand(123);
-        printf("%d\n", rand());
+    src = r'''#include <stdlib.h>
+#include <stdio.h>
+int main()
+{
+    srand(0xdeadbeef);
+    for(int i = 0; i < 10; ++i)
         printf("%d\n", rand());
 
-        unsigned state = 0;
-        int r;
-        r = rand_r(&state);
-        printf("%d, %u\n", r, state);
-        r = rand_r(&state);
-        printf("%d, %u\n", r, state);
-        state = 0;
-        r = rand_r(&state);
-        printf("%d, %u\n", r, state);
+    unsigned int seed = 0xdeadbeef;
+    for(int i = 0; i < 10; ++i)
+        printf("%d\n", rand_r(&seed));
 
-        return 0;
-      }
-      '''
-    expected = '''
-      1250496027
-      1116302336
-      440917656
-      1476150784
-      440917656
-      1476150784
-      12345, 12345
-      1406932606, 3554416254
-      12345, 12345
-      '''
-    self.do_run(src, re.sub(r'(^|\n)\s+', r'\1', expected))
+    return 0;
+}
+'''
+    expected = '''2073540312
+730128159
+1365227432
+1337224527
+792390264
+1952655743
+983994184
+1982845871
+1210574360
+1479617503
+2073540312
+730128159
+1365227432
+1337224527
+792390264
+1952655743
+983994184
+1982845871
+1210574360
+1479617503
+'''
+    self.do_run(src, expected)
 
   def test_strtod(self):
     if self.emcc_args is None: return self.skip('needs emcc for libc')