allow printing negative integers in cc_print (twitter#141)

* allow printing negative integers in cc_print

* fix overflow problem with llabs

* pick up seppo0010's optimization

include/cc_print.h

@@ -44,7 +44,10 @@ extern "C" {
 
 /* behavior undefined if there isn't enough space in buf */
 size_t cc_print_uint64_unsafe(char *buf, uint64_t n);
+size_t cc_print_int64_unsafe(char *buf, int64_t n);
+
 size_t cc_print_uint64(char *buf, size_t size, uint64_t n);
+size_t cc_print_int64(char *buf, size_t size, int64_t n);
 
 size_t _scnprintf(char *buf, size_t size, const char *fmt, ...);
 size_t _vscnprintf(char *buf, size_t size, const char *fmt, va_list args);

include/cc_util.h

@@ -57,13 +57,17 @@ extern "C" {
  * # define UINT16_MAX  (65535)
  * # define UINT32_MAX  (4294967295U)
  * # define UINT64_MAX  (__UINT64_C(18446744073709551615))
+ *
+ * # define INT64_MIN   -9223372036854775808LL
  */
 #define CC_UINT8_MAXLEN     (3 + 1)
 #define CC_UINT16_MAXLEN    (5 + 1)
 #define CC_UINT32_MAXLEN    (10 + 1)
 #define CC_UINT64_MAXLEN    (20 + 1)
 #define CC_UINTMAX_MAXLEN   CC_UINT64_MAXLEN
 
+#define CC_INT64_MAXLEN    (1 + 19 + 1)
+
 /* alignment */
 /* Make data 'd' or pointer 'p', n-byte aligned, where n is a power of 2 */
 #define CC_ALIGNMENT        sizeof(unsigned long) /* platform word */

src/cc_print.c

@@ -22,6 +22,9 @@
  * implementation as a reference (folly/Conv.h)
  */
 
+/* use our own macro instead of llabs() to make sure it works with INT64_MIN */
+#define abs_int64(_x) ((_x) >= 0 ? (_x) : -(_x))
+
 static inline void
 _print_uint64(char *buf, size_t d, uint64_t n)
 {
@@ -46,6 +49,22 @@ cc_print_uint64_unsafe(char *buf, uint64_t n)
     return d;
 }
 
+size_t
+cc_print_int64_unsafe(char *buf, int64_t n)
+{
+    size_t d;
+    uint64_t ab = abs_int64(n);
+
+    if (n < 0) {
+        *buf++ = '-';
+    }
+
+    d = digits(ab);
+    _print_uint64(buf, d, n);
+
+    return (n < 0) ? d + 1 : d;
+}
+
 size_t
 cc_print_uint64(char *buf, size_t size, uint64_t n)
 {
@@ -61,6 +80,27 @@ cc_print_uint64(char *buf, size_t size, uint64_t n)
     return d;
 }
 
+size_t
+cc_print_int64(char *buf, size_t size, int64_t n)
+{
+    size_t d;
+    uint64_t ab = abs_int64(n);
+
+    d =  digits(ab) + (n < 0);
+    if (size < d) {
+        return 0;
+    }
+
+    if (n < 0) {
+        *buf++ = '-';
+        d--;
+    }
+
+    _print_uint64(buf, d, n);
+
+    return (n < 0) ? d + 1 : d;
+}
+
 size_t
 _vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 {