diff options
Diffstat (limited to 'lib/lzo/lzo1x_compress.c')
| -rw-r--r-- | lib/lzo/lzo1x_compress.c | 226 |
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 000000000000..c935f00073e9 --- /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"); + |