add math/rand (#403)

c/math/rand

.gitignore

@@ -19,6 +19,7 @@ numpy.txt
 _go/
 _runtime/
 _tinygo/
+_output/
 build.dir/
 .vscode/
 

_demo/rand/rand.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/math/rand"
+)
+
+func main() {
+	var s c.Uint = 6
+	rand.Srand(s)
+	rr := rand.RandR(&s)
+	r := rand.Rand()
+	println("r:", r)
+	println("rr:", rr)
+}

c/math/rand/rand.go

@@ -0,0 +1,23 @@
+package rand
+
+import (
+	_ "unsafe"
+
+	"github.com/goplus/llgo/c"
+)
+
+const (
+	LLGoPackage = "decl"
+)
+
+//go:linkname Rand C.rand
+func Rand() c.Int
+
+//go:linkname RandR C.rand_r
+func RandR(*c.Uint) c.Int
+
+//go:linkname Srand C.srand
+func Srand(c.Uint)
+
+//go:linkname Sranddev C.sranddev
+func Sranddev()