diff options
Diffstat (limited to '')
-rw-r--r-- | lib/lzo/Makefile | 6 | ||||
-rw-r--r-- | lib/lzo/lzo1x_compress.c | 400 | ||||
-rw-r--r-- | lib/lzo/lzo1x_decompress_safe.c | 296 | ||||
-rw-r--r-- | lib/lzo/lzodefs.h | 71 |
4 files changed, 773 insertions, 0 deletions
diff --git a/lib/lzo/Makefile b/lib/lzo/Makefile new file mode 100644 index 000000000..2f58fafbb --- /dev/null +++ b/lib/lzo/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0-only +lzo_compress-objs := lzo1x_compress.o +lzo_decompress-objs := lzo1x_decompress_safe.o + +obj-$(CONFIG_LZO_COMPRESS) += lzo_compress.o +obj-$(CONFIG_LZO_DECOMPRESS) += lzo_decompress.o diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c new file mode 100644 index 000000000..8ad5ba2b8 --- /dev/null +++ b/lib/lzo/lzo1x_compress.c @@ -0,0 +1,400 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * LZO1X Compressor from LZO + * + * Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com> + * + * The full LZO package can be found at: + * http://www.oberhumer.com/opensource/lzo/ + * + * Changed for Linux kernel use by: + * Nitin Gupta <nitingupta910@gmail.com> + * Richard Purdie <rpurdie@openedhand.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <asm/unaligned.h> +#include <linux/lzo.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, + size_t ti, void *wrkmem, signed char *state_offset, + const unsigned char bitstream_version) +{ + const unsigned char *ip; + unsigned char *op; + const unsigned char * const in_end = in + in_len; + const unsigned char * const ip_end = in + in_len - 20; + const unsigned char *ii; + lzo_dict_t * const dict = (lzo_dict_t *) wrkmem; + + op = out; + ip = in; + ii = ip; + ip += ti < 4 ? 4 - ti : 0; + + for (;;) { + const unsigned char *m_pos = NULL; + size_t t, m_len, m_off; + u32 dv; + u32 run_length = 0; +literal: + ip += 1 + ((ip - ii) >> 5); +next: + if (unlikely(ip >= ip_end)) + break; + dv = get_unaligned_le32(ip); + + if (dv == 0 && bitstream_version) { + const unsigned char *ir = ip + 4; + const unsigned char *limit = ip_end + < (ip + MAX_ZERO_RUN_LENGTH + 1) + ? ip_end : ip + MAX_ZERO_RUN_LENGTH + 1; +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && \ + defined(LZO_FAST_64BIT_MEMORY_ACCESS) + u64 dv64; + + for (; (ir + 32) <= limit; ir += 32) { + dv64 = get_unaligned((u64 *)ir); + dv64 |= get_unaligned((u64 *)ir + 1); + dv64 |= get_unaligned((u64 *)ir + 2); + dv64 |= get_unaligned((u64 *)ir + 3); + if (dv64) + break; + } + for (; (ir + 8) <= limit; ir += 8) { + dv64 = get_unaligned((u64 *)ir); + if (dv64) { +# if defined(__LITTLE_ENDIAN) + ir += __builtin_ctzll(dv64) >> 3; +# elif defined(__BIG_ENDIAN) + ir += __builtin_clzll(dv64) >> 3; +# else +# error "missing endian definition" +# endif + break; + } + } +#else + while ((ir < (const unsigned char *) + ALIGN((uintptr_t)ir, 4)) && + (ir < limit) && (*ir == 0)) + ir++; + if (IS_ALIGNED((uintptr_t)ir, 4)) { + for (; (ir + 4) <= limit; ir += 4) { + dv = *((u32 *)ir); + if (dv) { +# if defined(__LITTLE_ENDIAN) + ir += __builtin_ctz(dv) >> 3; +# elif defined(__BIG_ENDIAN) + ir += __builtin_clz(dv) >> 3; +# else +# error "missing endian definition" +# endif + break; + } + } + } +#endif + while (likely(ir < limit) && unlikely(*ir == 0)) + ir++; + run_length = ir - ip; + if (run_length > MAX_ZERO_RUN_LENGTH) + run_length = MAX_ZERO_RUN_LENGTH; + } else { + t = ((dv * 0x1824429d) >> (32 - D_BITS)) & D_MASK; + m_pos = in + dict[t]; + dict[t] = (lzo_dict_t) (ip - in); + if (unlikely(dv != get_unaligned_le32(m_pos))) + goto literal; + } + + ii -= ti; + ti = 0; + t = ip - ii; + if (t != 0) { + if (t <= 3) { + op[*state_offset] |= t; + COPY4(op, ii); + op += t; + } else if (t <= 16) { + *op++ = (t - 3); + COPY8(op, ii); + COPY8(op + 8, ii + 8); + op += t; + } else { + if (t <= 18) { + *op++ = (t - 3); + } else { + size_t tt = t - 18; + *op++ = 0; + while (unlikely(tt > 255)) { + tt -= 255; + *op++ = 0; + } + *op++ = tt; + } + do { + COPY8(op, ii); + COPY8(op + 8, ii + 8); + op += 16; + ii += 16; + t -= 16; + } while (t >= 16); + if (t > 0) do { + *op++ = *ii++; + } while (--t > 0); + } + } + + if (unlikely(run_length)) { + ip += run_length; + run_length -= MIN_ZERO_RUN_LENGTH; + put_unaligned_le32((run_length << 21) | 0xfffc18 + | (run_length & 0x7), op); + op += 4; + run_length = 0; + *state_offset = -3; + goto finished_writing_instruction; + } + + m_len = 4; + { +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ64) + u64 v; + v = get_unaligned((const u64 *) (ip + m_len)) ^ + get_unaligned((const u64 *) (m_pos + m_len)); + if (unlikely(v == 0)) { + do { + m_len += 8; + v = get_unaligned((const u64 *) (ip + m_len)) ^ + get_unaligned((const u64 *) (m_pos + m_len)); + if (unlikely(ip + m_len >= ip_end)) + goto m_len_done; + } while (v == 0); + } +# if defined(__LITTLE_ENDIAN) + m_len += (unsigned) __builtin_ctzll(v) / 8; +# elif defined(__BIG_ENDIAN) + m_len += (unsigned) __builtin_clzll(v) / 8; +# else +# error "missing endian definition" +# endif +#elif defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ32) + u32 v; + v = get_unaligned((const u32 *) (ip + m_len)) ^ + get_unaligned((const u32 *) (m_pos + m_len)); + if (unlikely(v == 0)) { + do { + m_len += 4; + v = get_unaligned((const u32 *) (ip + m_len)) ^ + get_unaligned((const u32 *) (m_pos + m_len)); + if (v != 0) + break; + m_len += 4; + v = get_unaligned((const u32 *) (ip + m_len)) ^ + get_unaligned((const u32 *) (m_pos + m_len)); + if (unlikely(ip + m_len >= ip_end)) + goto m_len_done; + } while (v == 0); + } +# if defined(__LITTLE_ENDIAN) + m_len += (unsigned) __builtin_ctz(v) / 8; +# elif defined(__BIG_ENDIAN) + m_len += (unsigned) __builtin_clz(v) / 8; +# else +# error "missing endian definition" +# endif +#else + if (unlikely(ip[m_len] == m_pos[m_len])) { + do { + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (ip[m_len] != m_pos[m_len]) + break; + m_len += 1; + if (unlikely(ip + m_len >= ip_end)) + goto m_len_done; + } while (ip[m_len] == m_pos[m_len]); + } +#endif + } +m_len_done: + + m_off = ip - m_pos; + ip += m_len; + if (m_len <= M2_MAX_LEN && 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; + if (m_len <= M3_MAX_LEN) + *op++ = (M3_MARKER | (m_len - 2)); + else { + m_len -= M3_MAX_LEN; + *op++ = M3_MARKER | 0; + while (unlikely(m_len > 255)) { + m_len -= 255; + *op++ = 0; + } + *op++ = (m_len); + } + *op++ = (m_off << 2); + *op++ = (m_off >> 6); + } else { + m_off -= 0x4000; + if (m_len <= M4_MAX_LEN) + *op++ = (M4_MARKER | ((m_off >> 11) & 8) + | (m_len - 2)); + else { + if (unlikely(((m_off & 0x403f) == 0x403f) + && (m_len >= 261) + && (m_len <= 264)) + && likely(bitstream_version)) { + // Under lzo-rle, block copies + // for 261 <= length <= 264 and + // (distance & 0x80f3) == 0x80f3 + // can result in ambiguous + // output. Adjust length + // to 260 to prevent ambiguity. + ip -= m_len - 260; + m_len = 260; + } + m_len -= M4_MAX_LEN; + *op++ = (M4_MARKER | ((m_off >> 11) & 8)); + while (unlikely(m_len > 255)) { + m_len -= 255; + *op++ = 0; + } + *op++ = (m_len); + } + *op++ = (m_off << 2); + *op++ = (m_off >> 6); + } + *state_offset = -2; +finished_writing_instruction: + ii = ip; + goto next; + } + *out_len = op - out; + return in_end - (ii - ti); +} + +int lzogeneric1x_1_compress(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len, + void *wrkmem, const unsigned char bitstream_version) +{ + const unsigned char *ip = in; + unsigned char *op = out; + unsigned char *data_start; + size_t l = in_len; + size_t t = 0; + signed char state_offset = -2; + unsigned int m4_max_offset; + + // LZO v0 will never write 17 as first byte (except for zero-length + // input), so this is used to version the bitstream + if (bitstream_version > 0) { + *op++ = 17; + *op++ = bitstream_version; + m4_max_offset = M4_MAX_OFFSET_V1; + } else { + m4_max_offset = M4_MAX_OFFSET_V0; + } + + data_start = op; + + while (l > 20) { + size_t ll = l <= (m4_max_offset + 1) ? l : (m4_max_offset + 1); + uintptr_t ll_end = (uintptr_t) ip + ll; + if ((ll_end + ((t + ll) >> 5)) <= ll_end) + break; + BUILD_BUG_ON(D_SIZE * sizeof(lzo_dict_t) > LZO1X_1_MEM_COMPRESS); + memset(wrkmem, 0, D_SIZE * sizeof(lzo_dict_t)); + t = lzo1x_1_do_compress(ip, ll, op, out_len, t, wrkmem, + &state_offset, bitstream_version); + ip += ll; + op += *out_len; + l -= ll; + } + t += l; + + if (t > 0) { + const unsigned char *ii = in + in_len - t; + + if (op == data_start && t <= 238) { + *op++ = (17 + t); + } else if (t <= 3) { + op[state_offset] |= 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; + } + if (t >= 16) do { + COPY8(op, ii); + COPY8(op + 8, ii + 8); + op += 16; + ii += 16; + t -= 16; + } while (t >= 16); + if (t > 0) do { + *op++ = *ii++; + } while (--t > 0); + } + + *op++ = M4_MARKER | 1; + *op++ = 0; + *op++ = 0; + + *out_len = op - out; + return LZO_E_OK; +} + +int lzo1x_1_compress(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len, + void *wrkmem) +{ + return lzogeneric1x_1_compress(in, in_len, out, out_len, wrkmem, 0); +} + +int lzorle1x_1_compress(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len, + void *wrkmem) +{ + return lzogeneric1x_1_compress(in, in_len, out, out_len, + wrkmem, LZO_VERSION); +} + +EXPORT_SYMBOL_GPL(lzo1x_1_compress); +EXPORT_SYMBOL_GPL(lzorle1x_1_compress); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("LZO1X-1 Compressor"); diff --git a/lib/lzo/lzo1x_decompress_safe.c b/lib/lzo/lzo1x_decompress_safe.c new file mode 100644 index 000000000..7892a40cf --- /dev/null +++ b/lib/lzo/lzo1x_decompress_safe.c @@ -0,0 +1,296 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * LZO1X Decompressor from LZO + * + * Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com> + * + * The full LZO package can be found at: + * http://www.oberhumer.com/opensource/lzo/ + * + * Changed for Linux kernel use by: + * Nitin Gupta <nitingupta910@gmail.com> + * Richard Purdie <rpurdie@openedhand.com> + */ + +#ifndef STATIC +#include <linux/module.h> +#include <linux/kernel.h> +#endif +#include <asm/unaligned.h> +#include <linux/lzo.h> +#include "lzodefs.h" + +#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x)) +#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x)) +#define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun +#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun +#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun + +/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base + * count without overflowing an integer. The multiply will overflow when + * multiplying 255 by more than MAXINT/255. The sum will overflow earlier + * depending on the base count. Since the base count is taken from a u8 + * and a few bits, it is safe to assume that it will always be lower than + * or equal to 2*255, thus we can always prevent any overflow by accepting + * two less 255 steps. See Documentation/staging/lzo.rst for more information. + */ +#define MAX_255_COUNT ((((size_t)~0) / 255) - 2) + +int lzo1x_decompress_safe(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len) +{ + unsigned char *op; + const unsigned char *ip; + size_t t, next; + size_t state = 0; + const unsigned char *m_pos; + const unsigned char * const ip_end = in + in_len; + unsigned char * const op_end = out + *out_len; + + unsigned char bitstream_version; + + op = out; + ip = in; + + if (unlikely(in_len < 3)) + goto input_overrun; + + if (likely(in_len >= 5) && likely(*ip == 17)) { + bitstream_version = ip[1]; + ip += 2; + } else { + bitstream_version = 0; + } + + if (*ip > 17) { + t = *ip++ - 17; + if (t < 4) { + next = t; + goto match_next; + } + goto copy_literal_run; + } + + for (;;) { + t = *ip++; + if (t < 16) { + if (likely(state == 0)) { + if (unlikely(t == 0)) { + size_t offset; + const unsigned char *ip_last = ip; + + while (unlikely(*ip == 0)) { + ip++; + NEED_IP(1); + } + offset = ip - ip_last; + if (unlikely(offset > MAX_255_COUNT)) + return LZO_E_ERROR; + + offset = (offset << 8) - offset; + t += offset + 15 + *ip++; + } + t += 3; +copy_literal_run: +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) + if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) { + const unsigned char *ie = ip + t; + unsigned char *oe = op + t; + do { + COPY8(op, ip); + op += 8; + ip += 8; + COPY8(op, ip); + op += 8; + ip += 8; + } while (ip < ie); + ip = ie; + op = oe; + } else +#endif + { + NEED_OP(t); + NEED_IP(t + 3); + do { + *op++ = *ip++; + } while (--t > 0); + } + state = 4; + continue; + } else if (state != 4) { + next = t & 3; + m_pos = op - 1; + m_pos -= t >> 2; + m_pos -= *ip++ << 2; + TEST_LB(m_pos); + NEED_OP(2); + op[0] = m_pos[0]; + op[1] = m_pos[1]; + op += 2; + goto match_next; + } else { + next = t & 3; + m_pos = op - (1 + M2_MAX_OFFSET); + m_pos -= t >> 2; + m_pos -= *ip++ << 2; + t = 3; + } + } else if (t >= 64) { + next = t & 3; + m_pos = op - 1; + m_pos -= (t >> 2) & 7; + m_pos -= *ip++ << 3; + t = (t >> 5) - 1 + (3 - 1); + } else if (t >= 32) { + t = (t & 31) + (3 - 1); + if (unlikely(t == 2)) { + size_t offset; + const unsigned char *ip_last = ip; + + while (unlikely(*ip == 0)) { + ip++; + NEED_IP(1); + } + offset = ip - ip_last; + if (unlikely(offset > MAX_255_COUNT)) + return LZO_E_ERROR; + + offset = (offset << 8) - offset; + t += offset + 31 + *ip++; + NEED_IP(2); + } + m_pos = op - 1; + next = get_unaligned_le16(ip); + ip += 2; + m_pos -= next >> 2; + next &= 3; + } else { + NEED_IP(2); + next = get_unaligned_le16(ip); + if (((next & 0xfffc) == 0xfffc) && + ((t & 0xf8) == 0x18) && + likely(bitstream_version)) { + NEED_IP(3); + t &= 7; + t |= ip[2] << 3; + t += MIN_ZERO_RUN_LENGTH; + NEED_OP(t); + memset(op, 0, t); + op += t; + next &= 3; + ip += 3; + goto match_next; + } else { + m_pos = op; + m_pos -= (t & 8) << 11; + t = (t & 7) + (3 - 1); + if (unlikely(t == 2)) { + size_t offset; + const unsigned char *ip_last = ip; + + while (unlikely(*ip == 0)) { + ip++; + NEED_IP(1); + } + offset = ip - ip_last; + if (unlikely(offset > MAX_255_COUNT)) + return LZO_E_ERROR; + + offset = (offset << 8) - offset; + t += offset + 7 + *ip++; + NEED_IP(2); + next = get_unaligned_le16(ip); + } + ip += 2; + m_pos -= next >> 2; + next &= 3; + if (m_pos == op) + goto eof_found; + m_pos -= 0x4000; + } + } + TEST_LB(m_pos); +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) + if (op - m_pos >= 8) { + unsigned char *oe = op + t; + if (likely(HAVE_OP(t + 15))) { + do { + COPY8(op, m_pos); + op += 8; + m_pos += 8; + COPY8(op, m_pos); + op += 8; + m_pos += 8; + } while (op < oe); + op = oe; + if (HAVE_IP(6)) { + state = next; + COPY4(op, ip); + op += next; + ip += next; + continue; + } + } else { + NEED_OP(t); + do { + *op++ = *m_pos++; + } while (op < oe); + } + } else +#endif + { + unsigned char *oe = op + t; + NEED_OP(t); + op[0] = m_pos[0]; + op[1] = m_pos[1]; + op += 2; + m_pos += 2; + do { + *op++ = *m_pos++; + } while (op < oe); + } +match_next: + state = next; + t = next; +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) + if (likely(HAVE_IP(6) && HAVE_OP(4))) { + COPY4(op, ip); + op += t; + ip += t; + } else +#endif + { + NEED_IP(t + 3); + NEED_OP(t); + while (t > 0) { + *op++ = *ip++; + t--; + } + } + } + +eof_found: + *out_len = op - out; + return (t != 3 ? LZO_E_ERROR : + ip == ip_end ? LZO_E_OK : + ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN); + +input_overrun: + *out_len = op - out; + return LZO_E_INPUT_OVERRUN; + +output_overrun: + *out_len = op - out; + return LZO_E_OUTPUT_OVERRUN; + +lookbehind_overrun: + *out_len = op - out; + return LZO_E_LOOKBEHIND_OVERRUN; +} +#ifndef STATIC +EXPORT_SYMBOL_GPL(lzo1x_decompress_safe); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("LZO1X Decompressor"); + +#endif diff --git a/lib/lzo/lzodefs.h b/lib/lzo/lzodefs.h new file mode 100644 index 000000000..b60851fcf --- /dev/null +++ b/lib/lzo/lzodefs.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * lzodefs.h -- architecture, OS and compiler specific defines + * + * Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com> + * + * The full LZO package can be found at: + * http://www.oberhumer.com/opensource/lzo/ + * + * Changed for Linux kernel use by: + * Nitin Gupta <nitingupta910@gmail.com> + * Richard Purdie <rpurdie@openedhand.com> + */ + + +/* Version + * 0: original lzo version + * 1: lzo with support for RLE + */ +#define LZO_VERSION 1 + +#define COPY4(dst, src) \ + put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst)) +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64) +#define COPY8(dst, src) \ + put_unaligned(get_unaligned((const u64 *)(src)), (u64 *)(dst)) +#else +#define COPY8(dst, src) \ + COPY4(dst, src); COPY4((dst) + 4, (src) + 4) +#endif + +#if defined(__BIG_ENDIAN) && defined(__LITTLE_ENDIAN) +#error "conflicting endian definitions" +#elif defined(CONFIG_X86_64) || defined(CONFIG_ARM64) +#define LZO_USE_CTZ64 1 +#define LZO_USE_CTZ32 1 +#define LZO_FAST_64BIT_MEMORY_ACCESS +#elif defined(CONFIG_X86) || defined(CONFIG_PPC) +#define LZO_USE_CTZ32 1 +#elif defined(CONFIG_ARM) && (__LINUX_ARM_ARCH__ >= 5) +#define LZO_USE_CTZ32 1 +#endif + +#define M1_MAX_OFFSET 0x0400 +#define M2_MAX_OFFSET 0x0800 +#define M3_MAX_OFFSET 0x4000 +#define M4_MAX_OFFSET_V0 0xbfff +#define M4_MAX_OFFSET_V1 0xbffe + +#define M1_MIN_LEN 2 +#define M1_MAX_LEN 2 +#define M2_MIN_LEN 3 +#define M2_MAX_LEN 8 +#define M3_MIN_LEN 3 +#define M3_MAX_LEN 33 +#define M4_MIN_LEN 3 +#define M4_MAX_LEN 9 + +#define M1_MARKER 0 +#define M2_MARKER 64 +#define M3_MARKER 32 +#define M4_MARKER 16 + +#define MIN_ZERO_RUN_LENGTH 4 +#define MAX_ZERO_RUN_LENGTH (2047 + MIN_ZERO_RUN_LENGTH) + +#define lzo_dict_t unsigned short +#define D_BITS 13 +#define D_SIZE (1u << D_BITS) +#define D_MASK (D_SIZE - 1) +#define D_HIGH ((D_MASK >> 1) + 1) |