add api EncodeTo / DecodeTo

decode.go

@@ -51,8 +51,42 @@ func (bs Base) Decode(data []byte) (out []byte) {
 	return
 }
 
+func (bs Base) DecodeTo(data, out []byte) {
+	if len(data) == 0 || len(data)%2 != 0 {
+		return
+	}
+	if bits.OnesCount8(bs.bit) == 1 { // 2的幂永无offset, 无需管til (1/2/4/8)
+		switch bs.bit {
+		case 8:
+			dec16blk8(bs.off, data, out)
+		case 4:
+			mask := uint32(bs.off) | uint32(bs.off)<<16
+			dec32blk4(mask, data, out)
+		case 2:
+			mask := uint64(bs.off) | uint64(bs.off)<<16 | uint64(bs.off)<<32 | uint64(bs.off)<<48
+			dec64blk2(mask, data, out)
+		case 1:
+			mask64 := uint64(bs.off) | uint64(bs.off)<<16 | uint64(bs.off)<<32 | uint64(bs.off)<<48
+			mask := uint128be{a: mask64, b: mask64}
+			dec128blk1(mask, data, out)
+		}
+		return
+	}
+	switch bs.bit {
+	case 3, 5, 7, 9, 11, 13, 15:
+		mask64 := uint64(bs.off) | uint64(bs.off)<<16 | uint64(bs.off)<<32 | uint64(bs.off)<<48
+		mask := uint128be{a: mask64, b: mask64}
+		dec128blk(mask, bs.bit, data, out)
+	case 6, 10, 12, 14:
+		mask := uint64(bs.off) | uint64(bs.off)<<16 | uint64(bs.off)<<32 | uint64(bs.off)<<48
+		dec64blk(mask, bs.bit, data, out)
+	}
+}
+
 // dec64blk2 for bit 2
-//    len(in)>0, len(in)%8==0, len(out)==len(in)/8
+//
+//	len(in)>0, len(in)%8==0, len(out)==len(in)/8
+//
 //go:nosplit
 func dec64blk2(mask uint64, in, out []byte) {
 	for i := range out {
@@ -70,7 +104,9 @@ func dec64blk2(mask uint64, in, out []byte) {
 }
 
 // dec32blk4 for bit 4
-//    len(in)>0, len(in)%4==0, len(out)==len(in)/4
+//
+//	len(in)>0, len(in)%4==0, len(out)==len(in)/4
+//
 //go:nosplit
 func dec32blk4(mask uint32, in, out []byte) {
 	for i := range out {
@@ -84,7 +120,9 @@ func dec32blk4(mask uint32, in, out []byte) {
 }
 
 // dec16blk8 for bit 8
-//    len(in)>0, len(in)%2==0, len(out)==len(in)/2
+//
+//	len(in)>0, len(in)%2==0, len(out)==len(in)/2
+//
 //go:nosplit
 func dec16blk8(mask uint16, in, out []byte) {
 	for i := range out {
@@ -95,7 +133,9 @@ func dec16blk8(mask uint16, in, out []byte) {
 }
 
 // dec128blk for bit 3 5 6 7 9 11 13 15
-//    len(in)>0, len(in)%2==0, len(out)==len(in)/16*bit+offset
+//
+//	len(in)>0, len(in)%2==0, len(out)==len(in)/16*bit+offset
+//
 //go:nosplit
 func dec128blk(mask uint128be, bit uint8, in, out []byte) {
 	var tmp [16]byte
@@ -176,7 +216,9 @@ func dec128blk(mask uint128be, bit uint8, in, out []byte) {
 }
 
 // dec64blk for bit 6 10 12 14
-//    len(in)>0, len(in)%2==0, len(out)==len(in)/16*bit+offset
+//
+//	len(in)>0, len(in)%2==0, len(out)==len(in)/16*bit+offset
+//
 //go:nosplit
 func dec64blk(mask uint64, bit uint8, in, out []byte) {
 	var tmp [8]byte

encode.go

@@ -11,6 +11,20 @@ func (bs Base) Encode(data []byte) (out []byte) {
 		return nil
 	}
 	out = make([]byte, outlen)
+	bs.encode(data, out, outlen, offset)
+	return
+}
+
+// EncodeTo data to base2n
+func (bs Base) EncodeTo(data, out []byte) {
+	outlen, offset := bs.EncodeLen(len(data))
+	if outlen <= 0 || offset < 0 {
+		return
+	}
+	bs.encode(data, out, outlen, offset)
+}
+
+func (bs Base) encode(data, out []byte, outlen, offset int) {
 	switch bs.bit {
 	case 3, 5, 7, 9, 11, 13, 15:
 		mask64 := uint64(bs.off) | uint64(bs.off)<<16 | uint64(bs.off)<<32 | uint64(bs.off)<<48
@@ -33,11 +47,12 @@ func (bs Base) Encode(data []byte) (out []byte) {
 	if offset > 0 {
 		binary.BigEndian.PutUint16(out[outlen-2:outlen], bs.til+uint16(offset))
 	}
-	return
 }
 
 // enc128blk for bit 3 5 6 7 9 11 13 15
-//    len(in)>0, len(out)==len(in)/bit*16
+//
+//	len(in)>0, len(out)==len(in)/bit*16
+//
 //go:nosplit
 func enc128blk(mask uint128be, bit uint8, in, out []byte) {
 	// 由于最后一次处理有读取越界, 因此作扩展
@@ -113,7 +128,9 @@ func enc128blk(mask uint128be, bit uint8, in, out []byte) {
 }
 
 // enc64blk for bit 6 10 12 14
-//    len(in)>0, len(out)==len(in)/bit*16
+//
+//	len(in)>0, len(out)==len(in)/bit*16
+//
 //go:nosplit
 func enc64blk(mask uint64, bit uint8, in, out []byte) {
 	// 由于最后一次处理有读取越界, 因此作扩展