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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /include/asm-generic/word-at-a-time.h
Initial import
Diffstat (limited to 'include/asm-generic/word-at-a-time.h')
-rw-r--r--include/asm-generic/word-at-a-time.h56
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diff --git a/include/asm-generic/word-at-a-time.h b/include/asm-generic/word-at-a-time.h
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+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+/*
+ * This says "generic", but it's actually big-endian only.
+ * Little-endian can use more efficient versions of these
+ * interfaces, see for example
+ * arch/x86/include/asm/word-at-a-time.h
+ * for those.
+ */
+
+#include <linux/kernel.h>
+
+struct word_at_a_time {
+ const unsigned long high_bits, low_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
+
+/* Bit set in the bytes that have a zero */
+static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
+{
+ unsigned long mask = (val & c->low_bits) + c->low_bits;
+ return ~(mask | rhs);
+}
+
+#define create_zero_mask(mask) (mask)
+
+static inline long find_zero(unsigned long mask)
+{
+ long byte = 0;
+#ifdef CONFIG_64BIT
+ if (mask >> 32)
+ mask >>= 32;
+ else
+ byte = 4;
+#endif
+ if (mask >> 16)
+ mask >>= 16;
+ else
+ byte += 2;
+ return (mask >> 8) ? byte : byte + 1;
+}
+
+static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
+{
+ unsigned long rhs = val | c->low_bits;
+ *data = rhs;
+ return (val + c->high_bits) & ~rhs;
+}
+
+#ifndef zero_bytemask
+#define zero_bytemask(mask) (~1ul << __fls(mask))
+#endif
+
+#endif /* _ASM_WORD_AT_A_TIME_H */