1 files changed, 135 insertions, 0 deletions
diff --git a/sys/lib/string/itoa.c b/sys/lib/string/itoa.c
new file mode 100644
index 0000000..c344161
--- /dev/null
+++ b/sys/lib/string/itoa.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2023 Ian Marco Moffett and the VegaOS team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of VegaOS nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* $Id$ */
+
+#include <string.h>
+
+static char *itoa_base10_convert(int64_t value, char *buf);
+
+static char *
+itoa_base10_convert(int64_t value, char *buf)
+{
+        size_t i;
+        uint8_t tmp;
+        bool is_negative;
+
+        i = 0;
+        is_negative = false;
+
+        if (value == 0) {
+            buf[i++] = '0';
+            buf[i++] = '\0';
+        }
+
+        if (value < 0) {
+            /* Easier to handle positive numbers */
+            value *= -1;
+            is_negative = true;
+        }
+
+        while (value > 0) {
+            buf[i++] = '0' + (value % 10);
+            value /= 10;
+        }
+
+        if (is_negative) {
+            buf[i++] = '-';
+        }
+
+        buf[i--] = '\0';
+
+        /* Result is in reverse */
+        for (int j = 0; j < i; ++j, --i) {
+            tmp = buf[j];
+            buf[j] = buf[i];
+            buf[i] = tmp;
+        }
+
+        return buf;
+}
+
+static char *
+itoa_convert_base16(uint64_t n, char *buffer)
+{
+    bool pad;
+    uint8_t nibble;
+    uint8_t i, j, tmp;
+    const char *ascii_nums = "0123456789ABCDEF";
+
+    i = 0;
+    pad = false;
+
+    if (n == 0) {
+            /* Zero, no need to parse */
+            memcpy(buffer, "0x00\0", 5);
+            return buffer;
+    }
+    /* If one digit, pad out 2 later */
+    if (n < 0x10) {
+            pad = true;
+    }
+
+    while (n > 0) {
+            nibble = (uint8_t)n & 0x0F;
+            nibble = ascii_nums[nibble];
+            buffer[i++] = nibble;
+            n >>= 4;        /* Fetch next nibble */
+    }
+
+    if (pad) {
+            buffer[i++] = '0';
+    }
+
+    /* Add "0x" prefix */
+    buffer[i++] = 'x';
+    buffer[i++] = '0';
+    buffer[i--] = '\0';
+
+    /* Unreverse the result */
+    for (j = 0; j < i; ++j, --i) {
+            tmp = buffer[j];
+            buffer[j] = buffer[i];
+            buffer[i] = tmp;
+    }
+    return buffer;
+}
+
+char *
+itoa(int64_t value, char *buf, int base)
+{
+    switch (base) {
+        case 10:
+            return itoa_base10_convert(value, buf);
+        case 16:
+            return itoa_convert_base16(value, buf);
+        default:
+            return NULL;
+    }
+}