bufio: use copy - significant speedup for writers

R=r
https://golang.org/cl/167047

diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index 788e9b52bb9f96161bfd46884b2288dc38de2698..782bfe2c4891322ec31d5f0c22f08157b65d4453 100644 (file)
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -38,12 +38,6 @@ func (b BufSizeError) String() string {
        return "bufio: bad buffer size " + strconv.Itoa(int(b))
 }
 
-func copySlice(dst []byte, src []byte) {
-       for i := 0; i < len(dst); i++ {
-               dst[i] = src[i]
-       }
-}
-
 
 // Buffered input.
 
@@ -90,7 +84,7 @@ func NewReader(rd io.Reader) *Reader {
 func (b *Reader) fill() {
        // Slide existing data to beginning.
        if b.w > b.r {
-               copySlice(b.buf[0:b.w-b.r], b.buf[b.r:b.w]);
+               copy(b.buf[0:b.w-b.r], b.buf[b.r:b.w]);
                b.w -= b.r;
        } else {
                b.w = 0
@@ -135,7 +129,7 @@ func (b *Reader) Read(p []byte) (nn int, err os.Error) {
                if n > b.w-b.r {
                        n = b.w - b.r
                }
-               copySlice(p[0:n], b.buf[b.r:b.r+n]);
+               copy(p[0:n], b.buf[b.r:b.r+n]);
                p = p[n:];
                b.r += n;
                b.lastbyte = int(b.buf[b.r-1]);
@@ -307,10 +301,10 @@ func (b *Reader) ReadBytes(delim byte) (line []byte, err os.Error) {
        buf := make([]byte, n);
        n = 0;
        for i := 0; i < nfull; i++ {
-               copySlice(buf[n:n+len(full[i])], full[i]);
+               copy(buf[n:n+len(full[i])], full[i]);
                n += len(full[i]);
        }
-       copySlice(buf[n:n+len(frag)], frag);
+       copy(buf[n:n+len(frag)], frag);
        return buf, err;
 }
 
@@ -375,7 +369,7 @@ func (b *Writer) Flush() os.Error {
        }
        if e != nil {
                if n > 0 && n < b.n {
-                       copySlice(b.buf[0:b.n-n], b.buf[n:b.n])
+                       copy(b.buf[0:b.n-n], b.buf[n:b.n])
                }
                b.n -= n;
                b.err = e;
@@ -422,7 +416,7 @@ func (b *Writer) Write(p []byte) (nn int, err os.Error) {
                if n > len(p) {
                        n = len(p)
                }
-               copySlice(b.buf[b.n:b.n+n], p[0:n]);
+               copy(b.buf[b.n:b.n+n], p[0:n]);
                b.n += n;
                nn += n;
                p = p[n:];