Add LZO1X algorithm to the kernel

This is a hybrid version of the patch to add the LZO1X compression
algorithm to the kernel.  Nitin and myself have merged the best parts of
the various patches to form this version which we're both happy with (and
are jointly signing off).

The performance of this version is equivalent to the original minilzo code
it was based on.  Bytecode comparisons have also been made on ARM, i386 and
x86_64 with favourable results.

There are several users of LZO lined up including jffs2, crypto and reiser4
since its much faster than zlib.

Signed-off-by: Nitin Gupta <nitingupta910@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 226 insertions, 0 deletions

diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c
new file mode 100644
index 00000000000..c935f00073e
--- /dev/null
+++ b/lib/lzo/lzo1x_compress.c
@@ -0,0 +1,226 @@
+/*
+ *  LZO1X Compressor from MiniLZO
+ *
+ *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <markus@oberhumer.com>
+ *
+ *  The full LZO package can be found at:
+ *  http://www.oberhumer.com/opensource/lzo/
+ *
+ *  Changed for kernel use by:
+ *  Nitin Gupta <nitingupta910@gmail.com>
+ *  Richard Purdie <rpurdie@openedhand.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/lzo.h>
+#include <asm/unaligned.h>
+#include "lzodefs.h"
+
+static noinline size_t
+_lzo1x_1_do_compress(const unsigned char *in, size_t in_len,
+		unsigned char *out, size_t *out_len, void *wrkmem)
+{
+	const unsigned char * const in_end = in + in_len;
+	const unsigned char * const ip_end = in + in_len - M2_MAX_LEN - 5;
+	const unsigned char ** const dict = wrkmem;
+	const unsigned char *ip = in, *ii = ip;
+	const unsigned char *end, *m, *m_pos;
+	size_t m_off, m_len, dindex;
+	unsigned char *op = out;
+
+	ip += 4;
+
+	for (;;) {
+		dindex = ((0x21 * DX3(ip, 5, 5, 6)) >> 5) & D_MASK;
+		m_pos = dict[dindex];
+
+		if (m_pos < in)
+			goto literal;
+
+		if (ip == m_pos || (ip - m_pos) > M4_MAX_OFFSET)
+			goto literal;
+
+		m_off = ip - m_pos;
+		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
+			goto try_match;
+
+		dindex = (dindex & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f);
+		m_pos = dict[dindex];
+
+		if (m_pos < in)
+			goto literal;
+
+		if (ip == m_pos || (ip - m_pos) > M4_MAX_OFFSET)
+			goto literal;
+
+		m_off = ip - m_pos;
+		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
+			goto try_match;
+
+		goto literal;
+
+try_match:
+		if (get_unaligned((const unsigned short *)m_pos)
+				== get_unaligned((const unsigned short *)ip)) {
+			if (likely(m_pos[2] == ip[2]))
+					goto match;
+		}
+
+literal:
+		dict[dindex] = ip;
+		++ip;
+		if (unlikely(ip >= ip_end))
+			break;
+		continue;
+
+match:
+		dict[dindex] = ip;
+		if (ip != ii) {
+			size_t t = ip - ii;
+
+			if (t <= 3) {
+				op[-2] |= t;
+			} else if (t <= 18) {
+				*op++ = (t - 3);
+			} else {
+				size_t tt = t - 18;
+
+				*op++ = 0;
+				while (tt > 255) {
+					tt -= 255;
+					*op++ = 0;
+				}
+				*op++ = tt;
+			}
+			do {
+				*op++ = *ii++;
+			} while (--t > 0);
+		}
+
+		ip += 3;
+		if (m_pos[3] != *ip++ || m_pos[4] != *ip++
+				|| m_pos[5] != *ip++ || m_pos[6] != *ip++
+				|| m_pos[7] != *ip++ || m_pos[8] != *ip++) {
+			--ip;
+			m_len = ip - ii;
+
+			if (m_off <= M2_MAX_OFFSET) {
+				m_off -= 1;
+				*op++ = (((m_len - 1) << 5)
+						| ((m_off & 7) << 2));
+				*op++ = (m_off >> 3);
+			} else if (m_off <= M3_MAX_OFFSET) {
+				m_off -= 1;
+				*op++ = (M3_MARKER | (m_len - 2));
+				goto m3_m4_offset;
+			} else {
+				m_off -= 0x4000;
+
+				*op++ = (M4_MARKER | ((m_off & 0x4000) >> 11)
+						| (m_len - 2));
+				goto m3_m4_offset;
+			}
+		} else {
+			end = in_end;
+			m = m_pos + M2_MAX_LEN + 1;
+
+			while (ip < end && *m == *ip) {
+				m++;
+				ip++;
+			}
+			m_len = ip - ii;
+
+			if (m_off <= M3_MAX_OFFSET) {
+				m_off -= 1;
+				if (m_len <= 33) {
+					*op++ = (M3_MARKER | (m_len - 2));
+				} else {
+					m_len -= 33;
+					*op++ = M3_MARKER | 0;
+					goto m3_m4_len;
+				}
+			} else {
+				m_off -= 0x4000;
+				if (m_len <= M4_MAX_LEN) {
+					*op++ = (M4_MARKER
+						| ((m_off & 0x4000) >> 11)
+						| (m_len - 2));
+				} else {
+					m_len -= M4_MAX_LEN;
+					*op++ = (M4_MARKER
+						| ((m_off & 0x4000) >> 11));
+m3_m4_len:
+					while (m_len > 255) {
+						m_len -= 255;
+						*op++ = 0;
+					}
+
+					*op++ = (m_len);
+				}
+			}
+m3_m4_offset:
+			*op++ = ((m_off & 63) << 2);
+			*op++ = (m_off >> 6);
+		}
+
+		ii = ip;
+		if (unlikely(ip >= ip_end))
+			break;
+	}
+
+	*out_len = op - out;
+	return in_end - ii;
+}
+
+int lzo1x_1_compress(const unsigned char *in, size_t in_len, unsigned char *out,
+			size_t *out_len, void *wrkmem)
+{
+	const unsigned char *ii;
+	unsigned char *op = out;
+	size_t t;
+
+	if (unlikely(in_len <= M2_MAX_LEN + 5)) {
+		t = in_len;
+	} else {
+		t = _lzo1x_1_do_compress(in, in_len, op, out_len, wrkmem);
+		op += *out_len;
+	}
+
+	if (t > 0) {
+		ii = in + in_len - t;
+
+		if (op == out && t <= 238) {
+			*op++ = (17 + t);
+		} else if (t <= 3) {
+			op[-2] |= t;
+		} else if (t <= 18) {
+			*op++ = (t - 3);
+		} else {
+			size_t tt = t - 18;
+
+			*op++ = 0;
+			while (tt > 255) {
+				tt -= 255;
+				*op++ = 0;
+			}
+
+			*op++ = tt;
+		}
+		do {
+			*op++ = *ii++;
+		} while (--t > 0);
+	}
+
+	*op++ = M4_MARKER | 1;
+	*op++ = 0;
+	*op++ = 0;
+
+	*out_len = op - out;
+	return LZO_E_OK;
+}
+EXPORT_SYMBOL_GPL(lzo1x_1_compress);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LZO1X-1 Compressor");
+