rename the dump978 export file, add some example build instructions

dump978.go

@@ -3,6 +3,18 @@
 // that can be found in the LICENSE file.
 
 // Package dump978 wraps libdump978, a 978MHz UAT demodulator.
+//
+// Build example
+//
+// dump978.so:
+//   $ gcc -c -O2 -g -Wall -Werror -Ifec -fpic -DBUILD_LIB=1 dump978.c fec.c fec/decode_rs_char.c fec/init_rs_char.c
+//   $ gcc -shared -lm -o ../libdump978.so dump978.o fec.o decode_rs_char.o init_rs_char.o
+//
+// dump978 go wrapper:
+//   $ go build -o dump978.a dump978.go dump978_exports.go
+//
+// uat_read executable:
+//   $ go build uat_read.go
 
 package dump978
 
@@ -47,4 +59,4 @@ func ProcessDataFromChannel() {
 		inData := <-InChan
 		ProcessData(inData)
 	}
-}
+}

exports.go

@@ -1,41 +0,0 @@
-// Copyright (c) 2015 Joseph D Poirier
-// Distributable under the terms of The New BSD License
-// that can be found in the LICENSE file.
-
-// Package dump978 wraps libdump978, a 978MHz UAT demodulator.
-
-package dump978
-
-import (
-	"fmt"
-	"reflect"
-	"unsafe"
-)
-
-/*
-#include <stdint.h>
-#include "dump978/dump978.h"
-*/
-import "C"
-
-// OutChan is a buffered output channel for demodulated data.
-var OutChan = make(chan string, 100)
-
-//export dump978Cb
-func dump978Cb(updown C.char, data *C.uint8_t, length C.int) {
-	// c buffer to go slice without copying
-	var buf []byte
-
-	b := (*reflect.SliceHeader)((unsafe.Pointer(&buf)))
-	b.Cap = int(length)
-	b.Len = int(length)
-	b.Data = uintptr(unsafe.Pointer(data))
-
-	// copy incoming to outgoing
-	outData := string(updown)
-	for i := 0; i < int(length); i++ {
-		outData += fmt.Sprintf("%02x", buf[i])
-	}
-
-	OutChan <- outData
-}