6 files changed, 178 insertions, 0 deletions
diff --git a/libk/makefile b/libk/makefile
new file mode 100644
index 0000000..faf5b79
--- /dev/null
+++ b/libk/makefile
@@ -0,0 +1,11 @@
+
+CXX_OBJ := string.o stdlib/console.o
+
+libk.a: $(CXX_OBJ)
+	$(AR) rcs $@ $(CXX_OBJ)
+
+$(CXX_OBJ): %.o : %.cc
+	$(CXX) -target $(TARGET) $(CXX_FLAGS) -I$(CURDIR) -c $^ -o $@
+
+clean:
+	rm libk.a $(CXX_OBJ)
diff --git a/libk/stdlib.h b/libk/stdlib.h
new file mode 100644
index 0000000..3e6619d
--- /dev/null
+++ b/libk/stdlib.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <string.h>
+
+class Console {
+public:
+  virtual void write(const String &msg) = 0;
+};
+
+void console_set(Console *ptr);
+
+void printk(const String &msg);
+
+__attribute__((__noreturn__)) void abort();
diff --git a/libk/stdlib/console.cc b/libk/stdlib/console.cc
new file mode 100644
index 0000000..dbc9b86
--- /dev/null
+++ b/libk/stdlib/console.cc
@@ -0,0 +1,28 @@
+#include "stdlib.h"
+
+static Console *global_console = nullptr;
+
+void console_set(Console *ptr) {
+  if (ptr != nullptr) {
+    global_console = ptr;
+  }
+}
+
+void printk(const String &msg) {
+  if (global_console == nullptr)
+    return;
+
+  global_console->write(msg);
+}
+
+void abort() {
+  /*
+   * On gcc, a 'while(true) {}' will infinitely loop
+   * but clang will optimize it away on -O2 if it's empty
+   * therefore, add no-op
+   */
+  while (true) {
+    asm volatile("nop");
+  }
+  __builtin_unreachable();
+}
diff --git a/libk/string.cc b/libk/string.cc
new file mode 100644
index 0000000..5cd4bb2
--- /dev/null
+++ b/libk/string.cc
@@ -0,0 +1,26 @@
+#include "string.h"
+
+// TODO
+
+// int strcpy(char *dst, const char *stc);
+// void strcat(void *dst, const void *src);
+// char* strncpy(char *dest, const char *src, int length);
+// int strncmp(const char *s1, const char *s2, int c);
+
+/* strcmp - compare two C-strings */
+constexpr int strcmp(const char *s1, const char *s2)
+{
+    const auto s1_len = strlen(s1);
+    for(size_t i = 0; i < s1_len; ++i) {
+        if(s1[i] == s2[i]) continue;
+        if(s1[i] > s2[i]) return 1;
+        if(s1[i] < s2[i]) return -1;
+    }
+    return 0;
+}
+
+static_assert(strcmp("one", "one") == 0);
+static_assert(strcmp("one", "two") < 0);
+static_assert(strcmp("foo", "bar") > 0);
+
+
diff --git a/libk/string.h b/libk/string.h
new file mode 100644
index 0000000..deb6fde
--- /dev/null
+++ b/libk/string.h
@@ -0,0 +1,69 @@
+#pragma once
+#include "types.h"
+
+constexpr size_t strlen(const char *str) {
+  int len = 0;
+  while (str[len])
+    ++len;
+  return len;
+}
+
+/* reverse:  reverse string s in place */
+constexpr void reverse(char s[]) {
+  int i, j;
+  char c;
+
+  for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
+    c = s[i];
+    s[i] = s[j];
+    s[j] = c;
+  }
+}
+
+/* itoa:  convert n to characters in s */
+template <int base = 10> constexpr void itoa(int n, char s[]) {
+  int i, sign;
+
+  if ((sign = n) < 0) /* record sign */
+    n = -n;           /* make n positive */
+
+  i = 0;
+  do { /* generate digits in reverse order */
+    s[i++] = "0123456789abcdef"[n % base]; /* get next digit */
+  } while ((n /= base) > 0);               /* delete it */
+
+  if (sign < 0)
+    s[i++] = '-';
+
+  s[i] = '\0';
+
+  reverse(s);
+}
+
+class String {
+public:
+  class Iterator {
+    friend class String;
+
+  public:
+    char next() { return p->buffer[pos++]; }
+    operator bool() const { return (pos < p->m_length); }
+
+  private:
+    Iterator(const String *s) : p(s) {}
+
+    size_t pos = 0;
+    const String *p;
+  };
+
+  friend class Iterator;
+
+  String(const char *d) : buffer{d}, m_length{strlen(d)} {}
+  String(const char *d, size_t l) : buffer{d}, m_length{l} {}
+
+  Iterator begin() const { return Iterator(this); }
+
+private:
+  const char *const buffer;
+  const size_t m_length;
+};
diff --git a/libk/types.h b/libk/types.h
new file mode 100644
index 0000000..0818342
--- /dev/null
+++ b/libk/types.h
@@ -0,0 +1,30 @@
+#pragma once
+
+typedef unsigned short size_t;
+static_assert(sizeof(size_t) >= 2);
+
+
+typedef unsigned char uint8_t;
+static_assert(sizeof(uint8_t) == 1);
+
+typedef unsigned short uint16_t;
+static_assert(sizeof(uint16_t) == 2);
+
+typedef unsigned int uint32_t;
+static_assert(sizeof(uint32_t) == 4);
+
+//typedef unsigned long uint64_t;
+//static_assert(sizeof(uint64_t) == 8);
+
+
+typedef char int8_t;
+static_assert(sizeof(int8_t) == 1);
+
+typedef short int16_t;
+static_assert(sizeof(int16_t) == 2);
+
+typedef int int32_t;
+static_assert(sizeof(int32_t) == 4);
+
+//typedef long int64_t;
+//static_assert(sizeof(int64_t) == 8);