lib: add BreakIntoBlocks

* lib/blocks.go (BreakIntoBlocks): New function.

1 files changed, 32 insertions, 0 deletions

diff --git a/lib/blocks.go b/lib/blocks.go
new file mode 100644
index 0000000..3805d86
--- /dev/null
+++ b/lib/blocks.go
@@ -0,0 +1,32 @@
+// Copyright © 2020 rsiddharth <s@ricketyspace.net>
+// SPDX-License-Identifier: ISC
+
+package lib
+
+// Breaks 'cb' into blocks of 'keysize'
+func BreakIntoBlocks(cb []byte, keysize int) [][]byte {
+	if len(cb) < 1 {
+		return make([][]byte, 0)
+	}
+
+	// Compute the number of blocks.
+	nb := len(cb) / keysize
+	if len(cb)%keysize != 0 {
+		nb += 1
+	}
+	blocks := make([][]byte, nb)
+
+	for i, j, k := 0, 0, 0; i < len(cb); i++ {
+		if len(blocks[k]) == 0 {
+			blocks[k] = make([]byte, keysize)
+		}
+		blocks[k][j] = cb[i]
+
+		j += 1
+		if j == 8 {
+			j = 0
+			k += 1
+		}
+	}
+	return blocks
+}