1 files changed, 85 insertions, 0 deletions
diff --git a/src/tai64nfrac.c b/src/tai64nfrac.c
new file mode 100644
index 0000000..f3db977
--- /dev/null
+++ b/src/tai64nfrac.c
@@ -0,0 +1,85 @@
+#include "buffer.h"
+#include "stralloc.h"
+#include "exit.h"
+#include "readwrite.h"
+#include "open.h"
+#include "scan.h"
+#include "fmt.h"
+#include "getln.h"
+
+#define TAI64NLEN 24
+
+/** @file tai64nfrac
+    @brief Read a TAI64N external format timestamp from stdin and 
+           write fractional seconds since epoch (TAI, not UTC) to stdout.  
+           Return the characters after the timestamp. 
+  */
+
+char outbuf[64];
+buffer bo = BUFFER_INIT(write,1,outbuf,sizeof(outbuf));
+
+static void outs(char *s)
+{
+  if (buffer_puts(&bo,s) == -1) _exit(1);
+  if (buffer_flush(&bo) == -1) _exit(1);
+}
+
+static void outi(int i)
+{
+  char num[FMT_ULONG];
+
+  if (buffer_put(&bo,num,fmt_ulong(num,(unsigned long) i)) == -1) _exit(1);
+  if (buffer_flush(&bo) == -1) _exit(1);
+}
+
+char inbuf[1024];
+buffer bi = BUFFER_INIT(read,0,inbuf,sizeof(inbuf));
+
+int main(void)
+{
+  int c;
+  int i;
+  int match;
+  unsigned long u;
+  unsigned long seconds;  
+  unsigned long nanoseconds;
+  stralloc line = {0};
+
+/* Read from stdin */
+
+   buffer_init(&bi,read,0,inbuf,sizeof(inbuf));
+
+  for (;;) {
+    if (getln(&bi,&line,&match,'\n') != 0) _exit(1);
+    if (!match) break;
+    if (!stralloc_0(&line)) _exit(1);
+
+    seconds = 0;
+    nanoseconds = 0;
+    
+    if (line.s[0] == '@') {     /* tai64 timestamp */  
+      for (i = 1; i <= TAI64NLEN; i++) {
+        c = (int)line.s[i];
+        u = c - '0';
+        if (u >= 10) {
+          u = c - 'a';
+          if (u >= 6) break;
+          u += 10;
+        }
+        seconds <<= 4;
+        seconds += nanoseconds >> 28;
+        nanoseconds &= 0xfffffff;
+        nanoseconds <<= 4;
+        nanoseconds += u;
+      }
+      seconds -= 4611686018427387914ULL;
+      seconds = seconds > 0 ? seconds : 0;
+      outi(seconds); outs("."); outi(nanoseconds); outs(line.s + i); outs("\n");
+    } else {
+      outs("tai64nfrac: fatal: Wrong TAI64N input format."); outs("\n");
+      _exit(1);
+    }
+  }
+
+  _exit(0);
+}