Add bytor.go

Add bytor.go to convert between Java-style signed int bytes to normal
hex bytes.  For example a byte with value -1 in Java-speak has value
0xff in hex.

Signed-off-by: Colin McCabe <cmccabe@alumni.cmu.edu>

diff --git a/.gitignore b/.gitignore
index 85ab56e..65c02f9 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 #
 
 # binaries
+bytor
 errno_speak
 simple_time
 vimstart

diff --git a/Makefile b/Makefile
index e8baa16..20180f3 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,9 @@
 CFLAGS=-Wall -O2
 
-all:           errno_speak show_default_sockopts simple_time vimstart
+all:           bytor errno_speak show_default_sockopts simple_time vimstart
+
+bytor:
+       go build bytor.go
 
 errno_speak:   errno_speak.o
 

diff --git a/bytor.go b/bytor.go
new file mode 100644 (file)
index 0000000..c5f5689
--- /dev/null
+++ b/bytor.go
@@ -0,0 +1,46 @@
+package main
+
+import "fmt"
+import "os"
+import "strconv"
+
+func usage(retval int) {
+       fmt.Printf("bytor: converts bytes between hex and decimal.\n" +
+               "\n" +
+               "usage: bytor [flags] [number-to-convert]\n" +
+               "\n" +
+               "Numbers with the prefix '0x' will be interpreted as \n" +
+               "hexadecimal; others will be interpreted as decimal.\n" +
+               "\n" +
+               "Flags:\n" +
+               "-d:         Decimal output (default is hex.)\n" +
+               "-h/--help:  This help message\n")
+       os.Exit(retval)
+}
+
+func main() {
+       formatStr := "0x%02x\n"
+       i := 1
+       if (len(os.Args) < 2) {
+               usage(1)
+       }
+       if ((os.Args[i] == "-h") || (os.Args[i] == "--help")) {
+               usage(0)
+       }
+       if (os.Args[i] == "-d") {
+               formatStr = "%d\n"
+               i++
+       }
+       if (i >= len(os.Args)) {
+               usage(1)
+       }
+       val, err := strconv.ParseInt(os.Args[i], 0, 8)
+       if (err != nil) {
+               fmt.Printf("Error parsing input: %v\n", err)
+               os.Exit(1)
+       }
+       if (val < 0) {
+               val = 0x100 + val;
+       }
+       fmt.Printf(formatStr, val)
+}