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| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
|---|---|
| 2 | #ifndef _ASM_WORD_AT_A_TIME_H |
| 3 | #define _ASM_WORD_AT_A_TIME_H |
| 4 | |
| 5 | #include <linux/kernel.h> |
| 6 | #include <asm/byteorder.h> |
| 7 | |
| 8 | #ifdef __BIG_ENDIAN |
| 9 | |
| 10 | struct word_at_a_time { |
| 11 | const unsigned long high_bits, low_bits; |
| 12 | }; |
| 13 | |
| 14 | #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) } |
| 15 | |
| 16 | /* Bit set in the bytes that have a zero */ |
| 17 | static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c) |
| 18 | { |
| 19 | unsigned long mask = (val & c->low_bits) + c->low_bits; |
| 20 | return ~(mask | rhs); |
| 21 | } |
| 22 | |
| 23 | #define create_zero_mask(mask) (mask) |
| 24 | |
| 25 | static inline long find_zero(unsigned long mask) |
| 26 | { |
| 27 | long byte = 0; |
| 28 | #ifdef CONFIG_64BIT |
| 29 | if (mask >> 32) |
| 30 | mask >>= 32; |
| 31 | else |
| 32 | byte = 4; |
| 33 | #endif |
| 34 | if (mask >> 16) |
| 35 | mask >>= 16; |
| 36 | else |
| 37 | byte += 2; |
| 38 | return (mask >> 8) ? byte : byte + 1; |
| 39 | } |
| 40 | |
| 41 | static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c) |
| 42 | { |
| 43 | unsigned long rhs = val | c->low_bits; |
| 44 | *data = rhs; |
| 45 | return (val + c->high_bits) & ~rhs; |
| 46 | } |
| 47 | |
| 48 | #ifndef zero_bytemask |
| 49 | #define zero_bytemask(mask) (~1ul << __fls(mask)) |
| 50 | #endif |
| 51 | |
| 52 | #else |
| 53 | |
| 54 | /* |
| 55 | * The optimal byte mask counting is probably going to be something |
| 56 | * that is architecture-specific. If you have a reliably fast |
| 57 | * bit count instruction, that might be better than the multiply |
| 58 | * and shift, for example. |
| 59 | */ |
| 60 | struct word_at_a_time { |
| 61 | const unsigned long one_bits, high_bits; |
| 62 | }; |
| 63 | |
| 64 | #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } |
| 65 | |
| 66 | #ifdef CONFIG_64BIT |
| 67 | |
| 68 | /* |
| 69 | * Jan Achrenius on G+: microoptimized version of |
| 70 | * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" |
| 71 | * that works for the bytemasks without having to |
| 72 | * mask them first. |
| 73 | */ |
| 74 | static inline long count_masked_bytes(unsigned long mask) |
| 75 | { |
| 76 | return mask*0x0001020304050608ul >> 56; |
| 77 | } |
| 78 | |
| 79 | #else /* 32-bit case */ |
| 80 | |
| 81 | /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ |
| 82 | static inline long count_masked_bytes(long mask) |
| 83 | { |
| 84 | /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ |
| 85 | long a = (0x0ff0001+mask) >> 23; |
| 86 | /* Fix the 1 for 00 case */ |
| 87 | return a & mask; |
| 88 | } |
| 89 | |
| 90 | #endif |
| 91 | |
| 92 | /* Return nonzero if it has a zero */ |
| 93 | static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c) |
| 94 | { |
| 95 | unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; |
| 96 | *bits = mask; |
| 97 | return mask; |
| 98 | } |
| 99 | |
| 100 | static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c) |
| 101 | { |
| 102 | return bits; |
| 103 | } |
| 104 | |
| 105 | static inline unsigned long create_zero_mask(unsigned long bits) |
| 106 | { |
| 107 | bits = (bits - 1) & ~bits; |
| 108 | return bits >> 7; |
| 109 | } |
| 110 | |
| 111 | /* The mask we created is directly usable as a bytemask */ |
| 112 | #define zero_bytemask(mask) (mask) |
| 113 | |
| 114 | static inline unsigned long find_zero(unsigned long mask) |
| 115 | { |
| 116 | return count_masked_bytes(mask); |
| 117 | } |
| 118 | |
| 119 | #endif /* __BIG_ENDIAN */ |
| 120 | |
| 121 | #endif /* _ASM_WORD_AT_A_TIME_H */ |
| 122 |
Warning: This file is not a C or C++ file. It does not have highlighting.