Lots of CString clean up; attempt #1 at implementing int to string conversion

Long (64-bit) ints are hard to do on 32-bit...

src/kstd/CString.cc

@@ -13,10 +13,11 @@ namespace kstd {
 namespace CString {
 
 usize
-length(char* str)
+length(const char* str,
+       usize max)
 {
     usize i;
-    for (i = 0; str[i] != '\0'; i++);
+    for (i = 0; str[i] != '\0' && i < max; i++);
     return i;
 }
 
@@ -24,9 +25,10 @@ length(char* str)
 char*
 copy(char* dst,
      const char* src,
-     usize length)
+     usize max)
 {
-    for (usize i = 0; i < length; i++) {
+    usize len = length(src, max);
+    for (usize i = 0; i < len; i++) {
         dst[i] = src[i];
         if (src[i] == '\0') {
             break;
@@ -36,6 +38,23 @@ copy(char* dst,
 }
 
 
+char*
+reverse(char* str,
+        usize max)
+{
+    max = length(str, max);
+    char* p = str;
+    char* t = str + max - 1;
+    char c;
+    while (t > p) {
+        c = *p;
+        *p++ = *t;
+        *t-- = c;
+    }
+    return str;
+}
+
+
 void
 uppercase(char* str)
 {
@@ -50,12 +69,124 @@ uppercase(char *str)
  * Converters
  */
 
-char*
-fromInteger(int value,
-            char* str,
-            usize length)
+/**
+ * Converts `value` to an un-reversed CString without a null terminator. It is
+ * expected that callers of this function will append a null terminator and
+ * reverse `str` at the appropriate time.
+ *
+ * @return A pointer to the character *after* all converted characters, such
+ * that `p - buffer` is the number of characters converted.
+ */
+static usize
+_doConvertFromInteger(u32 value,
+                      char* buffer,
+                      usize length,
+                      u8 base,
+                      bool capitalized)
 {
-    return 0;
+    char* p = buffer;
+    int place;
+    do {
+        if (usize(p - buffer) >= length) {
+            break;
+        }
+        place = value % base;
+        value /= base;
+        *p++ = (place < 10) ? place + '0' : (place - 10) + (capitalized ? 'A' : 'a');
+    } while (value != 0);
+
+    return p - buffer;
+}
+
+char*
+fromInteger(i32 value,
+            char* buffer,
+            usize length,
+            u8 base,
+            bool capitalized)
+{
+    const bool negative = base == 10 && value < 0;
+    if (negative) {
+        value *= -1;
+    }
+
+    usize convertedLength = _doConvertFromInteger(u32(value), buffer, length, base, capitalized);
+
+    if (convertedLength < length && negative) {
+        buffer[convertedLength++] = '-';
+    }
+    if (convertedLength < length) {
+        buffer[convertedLength] = '\0';
+    }
+
+    reverse(buffer, convertedLength);
+
+    return buffer;
+}
+
+
+char*
+fromUnsignedInteger(u32 value,
+                    char* buffer,
+                    usize length,
+                    u8 base,
+                    bool capitalized)
+{
+    usize convertedLength = _doConvertFromInteger(u32(value), buffer, length, base, capitalized);
+    if (convertedLength < length) {
+        buffer[convertedLength] = '\0';
+    }
+    reverse(buffer, convertedLength);
+    return buffer;
+}
+
+
+char*
+fromLongInteger(i64 value,
+                char* buffer,
+                usize length,
+                u8 base,
+                bool capitalized)
+{
+    const bool negative = base == 10 && value < 0;
+    if (negative) {
+        value *= -1;
+    }
+
+    // Do large ints in two passes. First do the high-order bits, then the lower order bits.
+    usize convertedLength;
+    convertedLength  = _doConvertFromInteger(u32(value >> 32), buffer, length, base, capitalized);
+    convertedLength += _doConvertFromInteger(u32(value), &buffer[convertedLength], length - convertedLength, base, capitalized);
+
+    if (convertedLength < length && negative) {
+        buffer[convertedLength++] = '-';
+    }
+    if (convertedLength < length) {
+        buffer[convertedLength] = '\0';
+    }
+
+    reverse(buffer, convertedLength);
+
+    return buffer;
+}
+
+
+char*
+fromUnsignedLongInteger(u64 value,
+                        char* buffer,
+                        usize length,
+                        u8 base,
+                        bool capitalized)
+{
+    // Do large ints in two passes. First do the high-order bits, then the lower order bits.
+    usize convertedLength;
+    convertedLength  = _doConvertFromInteger(u32(value >> 32), buffer, length, base, capitalized);
+    convertedLength += _doConvertFromInteger(u32(value), &buffer[convertedLength], length - convertedLength, base, capitalized);
+    if (convertedLength < length) {
+        buffer[convertedLength] = '\0';
+    }
+    reverse(buffer, convertedLength);
+    return buffer;
 }
 
 

src/kstd/CString.hh

@@ -11,11 +11,20 @@
 namespace kstd {
 namespace CString {
 
-/** Find the length of a C string. */
-usize length(char *str);
+/**
+ * Find the length of a C string.
+ *
+ * @param [in] str  The string whose length we should find
+ * @param [in] max  Maximum number of characters to search
+ * @return Length of the string
+ */
+usize length(const char *str, usize max = -1);
 
 /** Copy a string. */
-char* copy(char* dst, const char* src, usize length);
+char* copy(char* dst, const char* src, usize max);
+
+/** Reverse a string. */
+char* reverse(char* str, usize max);
 
 /** Destructively convert an ASCII C String to uppercase. */
 void uppercase(char *str);
@@ -24,8 +33,21 @@ void uppercase(char *str);
  * @defgroup To-String Converters
  */
 
-/** Convert an integer to a string. */
-char* fromInteger(int value, char *str, usize length);
+/**
+ * Convert a signed integer to a string.
+ *
+ * @param [in]     value   The value to convert
+ * @param [in,out] buffer  Buffer to write to
+ * @param [in]     length  Length of the buffer
+ * @param [in]     base    Base to convert to. Default is base 10.
+ * @param [in]     capitalized  Should the alphabetic digits be capitalized? Default is false.
+ * @{
+ */
+char* fromInteger(i32 value, char* buffer, usize length, u8 base = 10, bool capitalized = false);
+char* fromUnsignedInteger(u32 value, char* buffer, usize length, u8 base = 10, bool capitalized = false);
+char* fromLongInteger(i64 value, char* buffer, usize length, u8 base = 10, bool capitalized = false);
+char* fromUnsignedLongInteger(u64 value, char* buffer, usize length, u8 base = 10, bool capitalized = false);
+/** @} */
 
 /** Convert a bool to a string. */
 char* fromBool(bool value, char* str, usize length);