Remove minio_calc_chunk_size() C code to write one in Golang

pkg/encoding/erasure/ec-common.h

@@ -19,14 +19,10 @@
 
 #include <stdint.h>
 
-#define SIMD_ALIGN 32
-
 int32_t minio_init_encoder (int technique, int k, int m,
                             uint8_t **encode_matrix,
                             uint8_t **encode_tbls);
 
-uint32_t minio_calc_chunk_size (int k, uint32_t split_len);
-
 int32_t minio_init_decoder (int32_t *error_index,
                             int k, int n, int errs,
                             uint8_t *encoding_matrix,

pkg/encoding/erasure/ec-decode.c

@@ -35,6 +35,7 @@ int32_t _minio_src_index_in_error (int r, int32_t *error_index)
         return 0;
 }
 
+// Separate out source data and target buffers
 int32_t minio_get_source_target (int errs, int k, int m,
                                  int32_t *error_index,
                                  uint32_t *decode_index,
@@ -95,7 +96,7 @@ int minio_init_decoder (int32_t *error_index,
                 tmp_decode_index[i] = r;
         }
 
-        // Not all Vandermonde matrix can be inverted
+        // Not all vandermonde matrix can be inverted
         if (gf_invert_matrix(input_matrix, inverse_matrix, k) < 0) {
                 return -1;
         }

pkg/encoding/erasure/ec-encode.c

@@ -20,6 +20,10 @@
 #include "ec-code.h"
 #include "ec-common.h"
 
+/*
+  Generate encode matrix during the encoding phase
+*/
+
 int32_t minio_init_encoder (int technique, int k, int m,
                             uint8_t **encode_matrix,
                             uint8_t **encode_tbls)
@@ -53,19 +57,3 @@ int32_t minio_init_encoder (int technique, int k, int m,
 
         return 0;
 }
-
-uint32_t minio_calc_chunk_size (int k, uint32_t split_len)
-{
-        int alignment;
-        int remainder;
-        int padded_len;
-
-        alignment = k * SIMD_ALIGN;
-        remainder = split_len % alignment;
-
-        padded_len = split_len;
-        if (remainder) {
-                padded_len = split_len + (alignment - remainder);
-        }
-        return padded_len / k;
-}

pkg/encoding/erasure/erasure_decode.go

@@ -39,12 +39,10 @@ func (e *Encoder) Decode(chunks [][]byte, length int) ([]byte, error) {
 
 	k := int(e.k)
 	n := int(e.k + e.m)
-
 	if len(chunks) != n {
 		return nil, errors.New(fmt.Sprintf("chunks length must be %d", n))
 	}
-
-	chunk_size := int(C.minio_calc_chunk_size(e.k, C.uint32_t(length)))
+	chunk_size := getChunkSize(k, length)
 
 	error_index := make([]int, n+1)
 	var err_count int = 0
@@ -97,6 +95,7 @@ func (e *Encoder) Decode(chunks [][]byte, length int) ([]byte, error) {
 		recovered_output = append(recovered_output, chunks[i]...)
 	}
 
+	// TODO cache this if necessary
 	e.decode_matrix = decode_matrix
 	e.decode_tbls = decode_tbls
 

pkg/encoding/erasure/erasure_encode.go

@@ -38,6 +38,10 @@ const (
 	M = 3
 )
 
+const (
+	SimdAlign = 32
+)
+
 // EncoderParams is a configuration set for building an encoder. It is created using ValidateParams.
 type EncoderParams struct {
 	K         uint8
@@ -112,15 +116,28 @@ func NewEncoder(ep *EncoderParams) *Encoder {
 	}
 }
 
+func getChunkSize(k, split_len int) int {
+	var alignment, remainder, padded_len int
+
+	alignment = k * SimdAlign
+	remainder = split_len % alignment
+
+	padded_len = split_len
+	if remainder != 0 {
+		padded_len = split_len + (alignment - remainder)
+	}
+	return padded_len / k
+}
+
 // Encode encodes a block of data. The input is the original data. The output
 // is a 2 tuple containing (k + m) chunks of erasure encoded data and the
 // length of the original object.
 func (e *Encoder) Encode(block []byte) ([][]byte, int) {
 	var block_len = len(block)
 
-	chunk_size := int(C.minio_calc_chunk_size(e.k, C.uint32_t(block_len)))
-	chunk_len := chunk_size * int(e.p.K)
-	pad_len := chunk_len - block_len
+	chunk_size := getChunkSize(int(e.k), block_len)
+	chunk_len := chunk_size * int(e.k)
+	pad_len := int(chunk_len) - block_len
 
 	if pad_len > 0 {
 		s := make([]byte, pad_len)