Add IntegerView

8 files changed, 147 insertions, 57 deletions

diff --git a/libk/makefile b/libk/makefile
index faf5b79..941d93d 100644
--- a/libk/makefile
+++ b/libk/makefile
@@ -1,11 +1,14 @@
 
 CXX_OBJ := string.o stdlib/console.o
+CXX_TEST_OBJ := type_traits/test.o
 
 libk.a: $(CXX_OBJ)
 	$(AR) rcs $@ $(CXX_OBJ)
 
-$(CXX_OBJ): %.o : %.cc
+test: $(CXX_TEST_OBJ)
+
+$(CXX_OBJ) $(CXX_TEST_OBJ): %.o : %.cc
 	$(CXX) -target $(TARGET) $(CXX_FLAGS) -I$(CURDIR) -c $^ -o $@
 
 clean:
-	rm libk.a $(CXX_OBJ)
+	rm -f libk.a $(CXX_OBJ) $(CXX_TEST_OBJ)
diff --git a/libk/stdlib.h b/libk/stdlib.h
index 44bacf4..f031408 100644
--- a/libk/stdlib.h
+++ b/libk/stdlib.h
@@ -4,27 +4,34 @@
 #include <type_traits.h>
 
 class Console {
-public:
+ public:
   virtual void write(char c) = 0;
-  virtual void write(const String &msg) = 0;
-  virtual void write(int n) = 0;
-  virtual void write(unsigned int n) = 0;
+  virtual void write(ViewIterator& msg) = 0;
 
-  static void set(Console *ptr);
-  static Console *get();
+  static void set(Console* ptr);
+  static Console* get();
 };
 
-template <typename T> void printk(const T &a) {
-  if (auto *c = Console::get()) {
-    if constexpr (is_same<T, const char *>())
-      c->write(String(a));
-    else
+template <typename T>
+void printk(const T& a) {
+  if (auto* c = Console::get()) {
+    if constexpr (is_same<T, char>()) {
+      c->write(a);
+    } else if constexpr (requires { StringView(a); }) {
+      StringView v(a);
+      auto iter = v.begin();
+      c->write(iter);
+    } else if constexpr (requires { IntegerView(a); }) {
+      IntegerView v(a);
+      auto iter = v.begin();
+      c->write(iter);
+    } else
       c->write(a);
   }
 }
 
 template <typename T, typename... Args>
-void printk(const T &a, const Args &...x) {
+void printk(const T& a, const Args&... x) {
   printk(a);
   printk(x...);
 }
diff --git a/libk/stdlib/console.cc b/libk/stdlib/console.cc
index dee6a8f..308f055 100644
--- a/libk/stdlib/console.cc
+++ b/libk/stdlib/console.cc
@@ -1,14 +1,16 @@
 #include "stdlib.h"
 
-static Console *global_console = nullptr;
+static Console* global_console = nullptr;
 
-void Console::set(Console *ptr) {
+void Console::set(Console* ptr) {
   if (ptr != nullptr) {
     global_console = ptr;
   }
 }
 
-Console *Console::get() { return global_console; }
+Console* Console::get() {
+  return global_console;
+}
 
 void abort() {
   /*
diff --git a/libk/string.cc b/libk/string.cc
index 5cd4bb2..c75feb1 100644
--- a/libk/string.cc
+++ b/libk/string.cc
@@ -8,19 +8,19 @@
 // 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;
+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
index deb6fde..0675cea 100644
--- a/libk/string.h
+++ b/libk/string.h
@@ -1,19 +1,24 @@
 #pragma once
-#include "types.h"
-
-constexpr size_t strlen(const char *str) {
-  int len = 0;
+#include <type_traits.h>
+#include <types.h>
+
+/**
+ * Calculate the length of the string (in bytes) pointed to by str, excluding
+ * the terminating null character.
+ */
+constexpr size_t strlen(const char* str) {
+  size_t len = 0;
   while (str[len])
     ++len;
   return len;
 }
 
 /* reverse:  reverse string s in place */
-constexpr void reverse(char s[]) {
+constexpr void reverse(char s[], int strlen) {
   int i, j;
   char c;
 
-  for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
+  for (i = 0, j = strlen - 1; i < j; i++, j--) {
     c = s[i];
     s[i] = s[j];
     s[j] = c;
@@ -21,49 +26,100 @@ constexpr void reverse(char s[]) {
 }
 
 /* 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 */
+template <typename T, int base = 10>
+constexpr size_t itoa(T n, char s[]) {
+  const bool is_negative = (n < 0);
+  if constexpr (!is_unsigned<T>()) {
+    if (n < 0)
+      n = -n;
+  }
 
-  i = 0;
-  do { /* generate digits in reverse order */
+  int 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)
+  if (is_negative)
     s[i++] = '-';
 
   s[i] = '\0';
 
-  reverse(s);
+  reverse(s, i);
+  return i;
 }
 
-class String {
+class ViewIterator {
 public:
-  class Iterator {
-    friend class String;
+  virtual char next() = 0;
+  virtual operator bool() const = 0;
+};
+
+class StringView {
+public:
+  class Iterator : public ViewIterator {
+    friend class StringView;
 
   public:
-    char next() { return p->buffer[pos++]; }
-    operator bool() const { return (pos < p->m_length); }
+    char next() override { return p->buffer[pos++]; }
+    operator bool() const override { return (pos < p->m_length); }
 
   private:
-    Iterator(const String *s) : p(s) {}
+    Iterator(const StringView* s) : p(s) {}
 
     size_t pos = 0;
-    const String *p;
+    const StringView* 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} {}
+  StringView(const char* d) : buffer{d}, m_length{strlen(d)} {}
+  StringView(const char* d, size_t l) : buffer{d}, m_length{l} {}
 
   Iterator begin() const { return Iterator(this); }
 
 private:
-  const char *const buffer;
+  const char* const buffer;
   const size_t m_length;
 };
+
+class IntegerView {
+public:
+  template <typename T>
+  struct HexFormat {
+    T n;
+  };
+
+  class Iterator : public ViewIterator {
+    friend class IntegerView;
+
+  public:
+    char next() override { return _p->buffer[pos++]; };
+    operator bool() const override { return (pos < _p->length); }
+
+  private:
+    Iterator(const IntegerView* v) : _p(v) {}
+
+    size_t pos = 0;
+    const IntegerView* _p;
+  };
+
+  IntegerView(int32_t n) { length = itoa(n, buffer); }
+
+  template <typename T>
+  IntegerView(HexFormat<T> f) {
+    buffer[0] = '0';
+    buffer[1] = 'x';
+    length = itoa<T, 16>(f.n, buffer + 2) + 2;
+  }
+
+  Iterator begin() const { return Iterator(this); }
+
+private:
+  char buffer[128];
+  size_t length = 0;
+};
+
+using hex = IntegerView::HexFormat<int32_t>;
+using uhex = IntegerView::HexFormat<uint32_t>;
+
+using hex_addr = IntegerView::HexFormat<uint64_t>;  // TODO causes crash
diff --git a/libk/type_traits.h b/libk/type_traits.h
index cef30c1..dc70339 100644
--- a/libk/type_traits.h
+++ b/libk/type_traits.h
@@ -1,10 +1,16 @@
 #pragma once
 
-template <class T, T v> struct integral_constant {
+template <class T, T v>
+struct integral_constant {
   constexpr T operator()() const { return v; }
   constexpr operator T() const { return v; }
 };
 
-template <class T, class U> struct is_same : integral_constant<bool, false> {};
+template <class T, class U>
+struct is_same : integral_constant<bool, false> {};
 
-template <class T> struct is_same<T, T> : integral_constant<bool, true> {};
+template <class T>
+struct is_same<T, T> : integral_constant<bool, true> {};
+
+template <typename T>
+struct is_unsigned : integral_constant<bool, (T{0} < static_cast<T>(-1))> {};
diff --git a/libk/type_traits/test.cc b/libk/type_traits/test.cc
new file mode 100644
index 0000000..1aa11df
--- /dev/null
+++ b/libk/type_traits/test.cc
@@ -0,0 +1,17 @@
+#include <type_traits.h>
+#include <types.h>
+
+// is_same
+static_assert(is_same<int, int>() == true);
+static_assert(is_same<int, unsigned int>() == false);
+
+// is_unsigned
+static_assert(is_unsigned<uint8_t>() == true);
+static_assert(is_unsigned<uint16_t>() == true);
+static_assert(is_unsigned<uint32_t>() == true);
+static_assert(is_unsigned<uint64_t>() == true);
+
+static_assert(is_unsigned<int8_t>() == false);
+static_assert(is_unsigned<int16_t>() == false);
+static_assert(is_unsigned<int32_t>() == false);
+static_assert(is_unsigned<int64_t>() == false);
diff --git a/libk/types.h b/libk/types.h
index be38cb0..fc20d22 100644
--- a/libk/types.h
+++ b/libk/types.h
@@ -3,7 +3,6 @@
 typedef unsigned short size_t;
 static_assert(sizeof(size_t) >= 2);
 
-
 typedef unsigned char uint8_t;
 static_assert(sizeof(uint8_t) == 1);