word-at-a-time.h

  1#ifndef _ASM_WORD_AT_A_TIME_H
  2#define _ASM_WORD_AT_A_TIME_H
  3
  4/*
  5 * Word-at-a-time interfaces for PowerPC.
  6 */
  7#include <linux/bitops.h>
  8#include <linux/wordpart.h>
  9#include <asm/asm-compat.h>
 10#include <asm/extable.h>
 11
 12#ifdef __BIG_ENDIAN__
 13
 14struct word_at_a_time {
 15	const unsigned long high_bits, low_bits;
 16};
 17
 18#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
 19
 20/* Bit set in the bytes that have a zero */
 21static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
 22{
 23	unsigned long mask = (val & c->low_bits) + c->low_bits;
 24	return ~(mask | rhs);
 25}
 26
 27#define create_zero_mask(mask) (mask)
 28
 29static inline long find_zero(unsigned long mask)
 30{
 31	long leading_zero_bits;
 32
 33	asm (PPC_CNTLZL "%0,%1" : "=r" (leading_zero_bits) : "r" (mask));
 34	return leading_zero_bits >> 3;
 35}
 36
 37static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
 38{
 39	unsigned long rhs = val | c->low_bits;
 40	*data = rhs;
 41	return (val + c->high_bits) & ~rhs;
 42}
 43
 44static inline unsigned long zero_bytemask(unsigned long mask)
 45{
 46	return ~1ul << __fls(mask);
 47}
 48
 49#else
 50
 51#ifdef CONFIG_64BIT
 52
 53/* unused */
 54struct word_at_a_time {
 55};
 56
 57#define WORD_AT_A_TIME_CONSTANTS { }
 58
 59/* This will give us 0xff for a NULL char and 0x00 elsewhere */
 60static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
 61{
 62	unsigned long ret;
 63	unsigned long zero = 0;
 64
 65	asm("cmpb %0,%1,%2" : "=r" (ret) : "r" (a), "r" (zero));
 66	*bits = ret;
 67
 68	return ret;
 69}
 70
 71static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
 72{
 73	return bits;
 74}
 75
 76/* Alan Modra's little-endian strlen tail for 64-bit */
 77static inline unsigned long create_zero_mask(unsigned long bits)
 78{
 79	unsigned long leading_zero_bits;
 80	long trailing_zero_bit_mask;
 81
 82	asm("addi	%1,%2,-1\n\t"
 83	    "andc	%1,%1,%2\n\t"
 84	    "popcntd	%0,%1"
 85		: "=r" (leading_zero_bits), "=&r" (trailing_zero_bit_mask)
 86		: "b" (bits));
 87
 88	return leading_zero_bits;
 89}
 90
 91static inline unsigned long find_zero(unsigned long mask)
 92{
 93	return mask >> 3;
 94}
 95
 96/* This assumes that we never ask for an all 1s bitmask */
 97static inline unsigned long zero_bytemask(unsigned long mask)
 98{
 99	return (1UL << mask) - 1;
100}
101
102#else	/* 32-bit case */
103
104struct word_at_a_time {
105	const unsigned long one_bits, high_bits;
106};
107
108#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
109
110/*
111 * This is largely generic for little-endian machines, but the
112 * optimal byte mask counting is probably going to be something
113 * that is architecture-specific. If you have a reliably fast
114 * bit count instruction, that might be better than the multiply
115 * and shift, for example.
116 */
117
118/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
119static inline long count_masked_bytes(long mask)
120{
121	/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
122	long a = (0x0ff0001+mask) >> 23;
123	/* Fix the 1 for 00 case */
124	return a & mask;
125}
126
127static inline unsigned long create_zero_mask(unsigned long bits)
128{
129	bits = (bits - 1) & ~bits;
130	return bits >> 7;
131}
132
133static inline unsigned long find_zero(unsigned long mask)
134{
135	return count_masked_bytes(mask);
136}
137
138/* Return nonzero if it has a zero */
139static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
140{
141	unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
142	*bits = mask;
143	return mask;
144}
145
146static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
147{
148	return bits;
149}
150
151/* The mask we created is directly usable as a bytemask */
152#define zero_bytemask(mask) (mask)
153
154#endif /* CONFIG_64BIT */
155
156#endif /* __BIG_ENDIAN__ */
157
158/*
159 * We use load_unaligned_zero() in a selftest, which builds a userspace
160 * program. Some linker scripts seem to discard the .fixup section, so allow
161 * the test code to use a different section name.
162 */
163#ifndef FIXUP_SECTION
164#define FIXUP_SECTION ".fixup"
165#endif
166
167static inline unsigned long load_unaligned_zeropad(const void *addr)
168{
169	unsigned long ret, offset, tmp;
170
171	asm(
172	"1:	" PPC_LL "%[ret], 0(%[addr])\n"
173	"2:\n"
174	".section " FIXUP_SECTION ",\"ax\"\n"
175	"3:	"
176#ifdef __powerpc64__
177	"clrrdi		%[tmp], %[addr], 3\n\t"
178	"clrlsldi	%[offset], %[addr], 61, 3\n\t"
179	"ld		%[ret], 0(%[tmp])\n\t"
180#ifdef __BIG_ENDIAN__
181	"sld		%[ret], %[ret], %[offset]\n\t"
182#else
183	"srd		%[ret], %[ret], %[offset]\n\t"
184#endif
185#else
186	"clrrwi		%[tmp], %[addr], 2\n\t"
187	"clrlslwi	%[offset], %[addr], 30, 3\n\t"
188	"lwz		%[ret], 0(%[tmp])\n\t"
189#ifdef __BIG_ENDIAN__
190	"slw		%[ret], %[ret], %[offset]\n\t"
191#else
192	"srw		%[ret], %[ret], %[offset]\n\t"
193#endif
194#endif
195	"b	2b\n"
196	".previous\n"
197	EX_TABLE(1b, 3b)
198	: [tmp] "=&b" (tmp), [offset] "=&r" (offset), [ret] "=&r" (ret)
199	: [addr] "b" (addr), "m" (*(unsigned long *)addr));
200
201	return ret;
202}
203
204#undef FIXUP_SECTION
205
206#endif /* _ASM_WORD_AT_A_TIME_H */