itoa

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@529 ec762483-ff6d-05da-a07a-a48fb63a330f

1 files changed, 100 insertions, 0 deletions

diff --git a/utils/utoa.h b/utils/utoa.h
new file mode 100755
index 00000000..6c1cf2de
--- /dev/null
+++ b/utils/utoa.h
@@ -0,0 +1,100 @@
+#ifndef UTOA_H
+#define UTOA_H
+
+#include <string>
+#include <cstring>
+
+#ifndef DIGIT_LOOKUP_TABLE
+# define DIGIT_LOOKUP_TABLE 0
+#endif
+
+const unsigned utoa_bufsize=21;
+const unsigned utoa_bufsizem1=utoa_bufsize-1;
+
+#ifdef DIGIT_LOOKUP_TABLE
+namespace {
+char digits[] = "0123456789";
+}
+#endif
+
+inline char digit_to_char(int d) {
+  return
+#ifdef DIGIT_LOOKUP_TABLE
+    digits[d];
+#else
+    '0'+d;
+#endif
+}
+
+// returns n in string [return,num); *num=0 yourself before calling if you want a c_str
+inline char *utoa(char *num,unsigned n) {
+  if ( !n ) {
+    *--num='0';
+  } else {
+    unsigned rem;
+    // 3digit lookup table, divide by 1000 faster?
+    while ( n ) {
+#if 1
+      rem = n;
+      n /= 10;
+      rem -= 10*n;		// maybe this is faster than mod because we are already dividing
+#else
+      rem = n%10; // would optimizer combine these together?
+      n   = n/10;
+#endif
+      *--num = digit_to_char(rem);
+    }
+  }
+  return num;
+}
+
+
+inline char *itoa(char *p,int n) {
+  if (n<0) {
+    p=utoa(p,-n); // TODO: check that (unsigned)(-INT_MIN) == 0x1000000 in 2s complement and not == 0
+    *--p='-';
+    return p;
+  } else
+    return utoa(p,n);
+}
+
+inline std::string utos(unsigned n) {
+  char buf[utoa_bufsize];
+  char *end=buf+utoa_bufsize;
+  char *p=utoa(end,n);
+  return std::string(p,end);
+}
+
+inline std::string itos(int n) {
+  char buf[utoa_bufsize];
+  char *end=buf+utoa_bufsize;
+  char *p=itoa(end,n);
+  return std::string(p,end);
+}
+
+//returns position of '\0' terminating number written starting at to
+inline char* append_utoa(char *to,unsigned n) {
+  char buf[utoa_bufsize];
+  char *end=buf+utoa_bufsize;
+  char *s=utoa(end,n);
+  int ns=end-s;
+  std::memcpy(to,s,ns);
+  to+=ns;
+  *to++=0;
+  return to;
+}
+
+//returns position of '\0' terminating number written starting at to
+inline char* append_itoa(char *to,unsigned n) {
+  char buf[utoa_bufsize];
+  char *end=buf+utoa_bufsize;
+  char *s=itoa(end,n);
+  int ns=end-s;
+  std::memcpy(to,s,ns);
+  to+=ns;
+  *to++=0;
+  return to;
+}
+
+
+#endif