add long long scanning support

scan/scan_longlong.c

@@ -0,0 +1,12 @@
+#include "scan.h"
+
+unsigned int scan_longlong(const char* src,signed long long* dest) {
+  unsigned int i,o;
+  unsigned long long l;
+  char c=src[0];
+  o=c=='-' || c=='+';
+  if ((i=scan_ulonglong(src+o,&l))) {
+    *dest=c=='-'?-l:l;
+    return i+o;
+  } return 0;
+}

scan/scan_ulonglong.c

@@ -0,0 +1,15 @@
+#include "scan.h"
+
+unsigned int scan_ulonglong(const char *src,unsigned long long *dest) {
+  register const char *tmp=src;
+  register unsigned long long l=0;
+  register unsigned char c;
+  while ((c=*tmp-'0')<10) {
+    unsigned long long m=l;
+    l=l*10+c;
+    if ((l>>3) < m) break;
+    ++tmp;
+  }
+  *dest=l;
+  return tmp-src;
+}