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Overview
Comment:Added a function that reverses the bits in a byte. Coverage: 100.0% of statements.
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SHA1: 2be2ff6bf747e4314ac4fa406b98faeb6970e8a8
User & Date: spaskalev on 2014-12-21 01:59:34.533
Other Links: manifest | tags
Context
2014-12-21
17:23
Fixed a rare case of losing data from the decompressor's internal result buffer. check-in: 7b74fd57f8 user: spaskalev tags: trunk
01:59
Added a function that reverses the bits in a byte. Coverage: 100.0% of statements. check-in: 2be2ff6bf7 user: spaskalev tags: trunk
2014-12-20
17:44
Buffer the input on decompressing, not the decompressor itself. This takes pdc -d < linux-3.18.1.tar.pdc > linux-3.18.1.tar down to 11 seconds from 13 minutes :) check-in: 4f0d26907d user: spaskalev tags: trunk
Changes
Side-by-Side Diff Ignore Whitespace Patch
Modified src/0dev.org/bits/bits.go from [3a25035ac5] to [7a154cae58].
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	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8}
	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
}

// Returns the number of raised bits in the given byte
func Hamming(b byte) byte {
	return hamming[b]
}

var reversed = [256]byte{
	0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112, 240,
	8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248,
	4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244,
	12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252,
	2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82, 210, 50, 178, 114, 242,
	10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250,
	6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246,
	14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254,
	1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81, 209, 49, 177, 113, 241,
	9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
	5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245,
	13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253,
	3, 131, 67, 195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243,
	11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251,
	7, 135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
	15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255,
}

// Returns a bits-reversed byte based on the input
func Reverse(b byte) byte {
	return reversed[b]
}

// The Vector interface defines methods on the bit vector
type Vector interface {
	// Retrieves the bit at the designated position
	Peek(uint) bool
	// Sets the bit at the designated position
	Poke(uint, bool)
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Modified src/0dev.org/bits/bits_test.go from [b5ed7a9a33] to [255f42be62].
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			b = b >> 1
		}
		if result != Hamming(byte(i)) {
			t.Error("Invalid hamming weight reported for ", i)
		}
	}
}

func TestReverse(t *testing.T) {
	for i := 0; i < 256; i++ {
		input, result := i, byte(0)
		for j := 0; j < 7; j++ {
			if (input & 1) > 0 {
				result |= 1
			}
			result <<= 1
			input >>= 1
		}
		if (input & 1) > 0 {
			result |= 1
		}
		if result != Reverse(byte(i)) {
			t.Error("Invalid reverse byte reported for ", i)
		}
	}
}

var sizes []uint = []uint{0, 31, 32, 33, 61, 63, 64, 127, 128, 129}

func TestBitSize(t *testing.T) {
	for _, size := range sizes {
		v := NewBit(size)
		if v.Len() < size || v.Len() > size+strconv.IntSize {
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