Move consts, ipfs, and ipld to pkg (#508)

* move ipfs and ipld packages to new pkg/da/

* moved consts to pkg

* clean up

pkg/consts/consts.go

@@ -0,0 +1,64 @@
+package consts
+
+import (
+	"crypto/sha256"
+
+	"github.com/celestiaorg/nmt/namespace"
+)
+
+// This contains all constants of:
+// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+const (
+	// ShareSize is the size of a share (in bytes).
+	// see: https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+	ShareSize = 256
+
+	// NamespaceSize is the namespace size in bytes.
+	NamespaceSize = 8
+
+	// ShareReservedBytes is the reserved bytes for contiguous appends.
+	ShareReservedBytes = 1
+
+	// TxShareSize is the number of bytes usable for tx/evidence/ISR shares.
+	TxShareSize = ShareSize - NamespaceSize - ShareReservedBytes
+	// MsgShareSize is the number of bytes usable for message shares.
+	MsgShareSize = ShareSize - NamespaceSize
+
+	// MaxSquareSize is the maximum number of
+	// rows/columns of the original data shares in square layout.
+	// Corresponds to AVAILABLE_DATA_ORIGINAL_SQUARE_MAX in the spec.
+	// 128*128*256 = 4 Megabytes
+	// TODO(ismail): settle on a proper max square
+	MaxSquareSize = 128
+
+	// MinSquareSize depicts the smallest original square width.
+	MinSquareSize = 1
+	MinSharecount = MinSquareSize * MinSquareSize
+)
+
+var (
+	// See spec for further details on the types of available data
+	// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#reserved-namespace-ids
+	// https://github.com/celestiaorg/celestia-specs/blob/de5f4f74f56922e9fa735ef79d9e6e6492a2bad1/specs/data_structures.md#availabledata
+
+	// TxNamespaceID is the namespace reserved for transaction data
+	TxNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 1}
+	// IntermediateStateRootsNamespaceID is the namespace reserved for
+	// intermediate state root data
+	IntermediateStateRootsNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 2}
+	// EvidenceNamespaceID is the namespace reserved for evidence
+	EvidenceNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 3}
+	// MaxReservedNamespace is the lexicographically largest namespace that is
+	// reserved for protocol use. It is derived from NAMESPACE_ID_MAX_RESERVED
+	// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+	MaxReservedNamespace = namespace.ID{0, 0, 0, 0, 0, 0, 0, 255}
+	// TailPaddingNamespaceID is the namespace ID for tail padding. All data
+	// with this namespace will be ignored
+	TailPaddingNamespaceID = namespace.ID{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE}
+
+	// ParitySharesNamespaceID indicates that share contains erasure data
+	ParitySharesNamespaceID = namespace.ID{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}
+
+	// NewBaseHashFunc change accordingly if another hash.Hash should be used as a base hasher in the NMT:
+	NewBaseHashFunc = sha256.New
+)