Tested each sample.

gem/gem.c

@@ -0,0 +1,54 @@
+#include "lua.h"
+#include "lauxlib.h"
+
+#define CR '\xD'
+#define LF '\xA'
+#define CRLF "\xD\xA"
+
+#define candidate(c) (c == CR || c == LF)
+static int pushchar(int c, int last, const char *marker, 
+    luaL_Buffer *buffer) {
+  if (candidate(c)) {
+    if (candidate(last)) {
+      if (c == last) 
+        luaL_addstring(buffer, marker);
+      return 0;
+    } else {
+      luaL_addstring(buffer, marker);
+      return c;
+    }
+  } else {
+    luaL_putchar(buffer, c);
+    return 0;
+  }
+}
+
+static int eol(lua_State *L) {
+  int context = luaL_checkint(L, 1);
+  size_t isize = 0;
+  const char *input = luaL_optlstring(L, 2, NULL, &isize);
+  const char *last = input + isize;
+  const char *marker = luaL_optstring(L, 3, CRLF);
+  luaL_Buffer buffer;
+  luaL_buffinit(L, &buffer);
+  if (!input) {
+    lua_pushnil(L);
+    lua_pushnumber(L, 0);
+    return 2;
+  }
+  while (input < last)
+    context = pushchar(*input++, context, marker, &buffer);
+  luaL_pushresult(&buffer);
+  lua_pushnumber(L, context);
+  return 2;
+}
+
+static luaL_reg func[] = {
+    { "eol", eol },
+    { NULL, NULL }
+};
+
+int luaopen_gem(lua_State *L) {
+    luaL_openlib(L, "gem", func, 0);
+	return 0;
+}