lcm

3 files changed, 64 insertions, 0 deletions

diff --git a/src/math.c b/src/math.c
new file mode 100644
index 0000000..3e36e3b
--- /dev/null
+++ b/src/math.c
@@ -0,0 +1,48 @@
+/*local function gcd(a,b)
+  if b == 0 then return a end
+  return gcd(b, math.fmod(a, b))
+end
+
+local function lcm(a)
+  local out = a[1]
+
+  for i=2,#a do
+    out = ((a[i] * out)) / (gcd(a[i], out))
+  end
+  return out
+end
+*/
+#include "math.h"
+#include "stdint.h"
+#include <stdlib.h>
+
+uint64_t gcd(uint64_t a, uint64_t b){
+  if(b == 0) return a;
+  return gcd(b, a % b);
+}
+
+uint64_t lcm(uint64_t* a, size_t len){
+  uint64_t out = a[0];
+  
+  for(size_t i = 1; i != len; i++){
+    out = (a[i] * out) / gcd(a[i], out);
+  }
+  return out;
+}
+
+int l_lcm(lua_State* L){
+  luaL_checktype(L, 1, LUA_TTABLE);
+  size_t len = lua_objlen(L,1); 
+  uint64_t* nums = malloc(sizeof * nums * len);
+  for(size_t i = 0; i <= len-1; i++){
+
+    lua_pushinteger(L,i+1);
+    lua_gettable(L,1);
+       
+    nums[i] = luaL_checknumber(L, -1);
+    lua_pop(L,1);
+  }
+  lua_pushnumber(L, lcm(nums, len));
+  free(nums);
+  return 1;
+}
diff --git a/src/math.h b/src/math.h
new file mode 100644
index 0000000..cfce896
--- /dev/null
+++ b/src/math.h
@@ -0,0 +1,11 @@
+#include "lua.h"
+
+int l_lcm(lua_State*);
+int l_gcd(lua_State*);
+
+static const luaL_Reg math_function_list [] = {
+  {"lcm",l_lcm},
+  //{"gcd",l_gcd},
+  
+  {NULL,NULL}
+};
diff --git a/src/reg.c b/src/reg.c
index 50dc8b9..e443cae 100644
--- a/src/reg.c
+++ b/src/reg.c
@@ -2,6 +2,7 @@
 #include "table.h"
 #include "crypto.h"
 #include "io.h"
+#include "math.h"
 
 int luaopen_llib(lua_State* L) { 
     lua_newtable(L);
@@ -18,6 +19,10 @@ int luaopen_llib(lua_State* L) {
     lua_newtable(L);
     luaL_register(L, NULL, io_function_list);
     lua_setfield(L, 2, "io");
+
+    lua_newtable(L);
+    luaL_register(L, NULL, math_function_list);
+    lua_setfield(L, 2, "math");
     //make llib global
     lua_setglobal(L, "llib");
     return 1;