1 #ifndef _ASM_WORD_AT_A_TIME_H
2 #define _ASM_WORD_AT_A_TIME_H
5 * Word-at-a-time interfaces for PowerPC.
8 #include <linux/kernel.h>
9 #include <asm/asm-compat.h>
13 struct word_at_a_time {
14 const unsigned long high_bits, low_bits;
17 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
19 /* Bit set in the bytes that have a zero */
20 static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
22 unsigned long mask = (val & c->low_bits) + c->low_bits;
26 #define create_zero_mask(mask) (mask)
28 static inline long find_zero(unsigned long mask)
30 long leading_zero_bits;
32 asm (PPC_CNTLZL "%0,%1" : "=r" (leading_zero_bits) : "r" (mask));
33 return leading_zero_bits >> 3;
36 static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
38 unsigned long rhs = val | c->low_bits;
40 return (val + c->high_bits) & ~rhs;
46 * This is largely generic for little-endian machines, but the
47 * optimal byte mask counting is probably going to be something
48 * that is architecture-specific. If you have a reliably fast
49 * bit count instruction, that might be better than the multiply
50 * and shift, for example.
52 struct word_at_a_time {
53 const unsigned long one_bits, high_bits;
56 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
61 * Jan Achrenius on G+: microoptimized version of
62 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
63 * that works for the bytemasks without having to
66 static inline long count_masked_bytes(unsigned long mask)
68 return mask*0x0001020304050608ul >> 56;
71 #else /* 32-bit case */
73 /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
74 static inline long count_masked_bytes(long mask)
76 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
77 long a = (0x0ff0001+mask) >> 23;
78 /* Fix the 1 for 00 case */
84 /* Return nonzero if it has a zero */
85 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
87 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
92 static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
97 static inline unsigned long create_zero_mask(unsigned long bits)
99 bits = (bits - 1) & ~bits;
103 /* The mask we created is directly usable as a bytemask */
104 #define zero_bytemask(mask) (mask)
106 static inline unsigned long find_zero(unsigned long mask)
108 return count_masked_bytes(mask);
112 #endif /* _ASM_WORD_AT_A_TIME_H */