fixed Makefile and preparation for release

Makefile

@@ -1,8 +1,8 @@
 build:
-	go build -o fastcommp
+	go build -o fastcommp cmd/main.go
 
 run:
-	go run main.go
+	go run cmd/main.go
 
 clean:
 	rm ./fastcommp 8G-payload.bin

README.md

@@ -2,6 +2,18 @@
 
 Filecoin fast piece commitment summation tool.
 
+# usage
+
+```go
+    fast := new(fastcommp.CommpWriter)
+	fast.Write(data)
+	sum, err := fast.Sum()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("commP: %s\n", sum.PieceCID.String())
+```
+
 # build
 
 `make build`

cmd/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"time"
+
+	"github.com/application-research/fastcommp"
+)
+
+func main() {
+	// Get the file name from the command-line arguments
+	if len(os.Args) != 2 {
+		fmt.Printf("Usage: %s <filename>\n", os.Args[0])
+		return
+	}
+	fileName := os.Args[1]
+
+	start := time.Now()
+	data, err := ioutil.ReadFile(fileName)
+	if err != nil {
+		fmt.Println("Error reading file:", err)
+		return
+	}
+
+	elapsed := time.Since(start)
+	fmt.Printf("Elapsed file read time: %s\n", elapsed)
+
+	fast := new(fastcommp.CommpWriter)
+	start = time.Now()
+	fast.Write(data)
+	sum, err := fast.Sum()
+	if err != nil {
+		panic(err)
+	}
+
+	elapsed = time.Since(start)
+	fmt.Printf("Elapsed commP time: %s\n", elapsed)
+	fmt.Printf("commP: %s\n", sum.PieceCID.String())
+
+	// Convert the sum results to a JSON string
+	results, err := json.MarshalIndent(sum, "", "  ")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(string(results))
+
+}

fastcommp.go

@@ -27,16 +27,16 @@ type DataCIDSize struct {
 const commPBufPad = abi.PaddedPieceSize(8 << 20)
 
 // CommPBuf is the size of the buffer used to calculate commP
-const CommPBuf = abi.UnpaddedPieceSize(commPBufPad - (commPBufPad / 128)) // can't use .Unpadded() for const
+const CommPBuf = abi.UnpaddedPieceSize(commPBufPad - (commPBufPad / 128))
 
 // ciderr is a cid and an error
 type ciderr struct {
 	c   cid.Cid
 	err error
 }
 
-// DataCidWriter is a writer that calculates the CommP
-type DataCidWriter struct {
+// CommpWriter is a writer that calculates the CommP
+type CommpWriter struct {
 	len    int64
 	buf    [CommPBuf]byte
 	leaves []chan ciderr
@@ -46,7 +46,7 @@ type DataCidWriter struct {
 }
 
 // Write writes data to the DataCidWriter
-func (w *DataCidWriter) Write(p []byte) (int, error) {
+func (w *CommpWriter) Write(p []byte) (int, error) {
 	if w.throttle == nil {
 		w.throttle = make(chan int, runtime.NumCPU())
 	}
@@ -57,6 +57,7 @@ func (w *DataCidWriter) Write(p []byte) (int, error) {
 		w.tbufs = make([][CommPBuf]byte, cap(w.throttle))
 	}
 
+	// process last non-zero leaf if exists and we have data to write
 	n := len(p)
 	for len(p) > 0 {
 		buffered := int(w.len % int64(len(w.buf)))
@@ -69,16 +70,19 @@ func (w *DataCidWriter) Write(p []byte) (int, error) {
 		p = p[copied:]
 		w.len += int64(copied)
 
+		// if we filled the buffer, process it
 		if copied > 0 && w.len%int64(len(w.buf)) == 0 {
 			leaf := make(chan ciderr, 1)
 			bufIdx := <-w.throttle
 			copy(w.tbufs[bufIdx][:], w.buf[:])
 
+			// process leaf in a goroutine
 			go func() {
 				defer func() {
 					w.throttle <- bufIdx
 				}()
 
+				// calculate commP for this leaf and send it to the channel
 				cc := new(commp.Calc)
 				_, _ = cc.Write(w.tbufs[bufIdx][:])
 				p, _, _ := cc.Digest()
@@ -89,17 +93,19 @@ func (w *DataCidWriter) Write(p []byte) (int, error) {
 				}
 			}()
 
+			// add leaf to list
 			w.leaves = append(w.leaves, leaf)
 		}
 	}
 	return n, nil
 }
 
-func (w *DataCidWriter) Sum() (DataCIDSize, error) {
+func (w *CommpWriter) Sum() (DataCIDSize, error) {
 	// process last non-zero leaf if exists
 	lastLen := w.len % int64(len(w.buf))
 	rawLen := w.len
 
+	// wait for all leaves to finish
 	leaves := make([]cid.Cid, len(w.leaves))
 	for i, leaf := range w.leaves {
 		r := <-leaf