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authorMichael I. Bushnell <mib@gnu.org>1995-08-03 16:12:24 +0000
committerMichael I. Bushnell <mib@gnu.org>1995-08-03 16:12:24 +0000
commit4321c1dec435027876cf89a25aedeb68b67275cf (patch)
tree7c1746e9f3963c67dc892493501e3dc7fb8c2581 /pfinet/asm
parentcaa08437b2414b3da188d75de274f51ff29382cb (diff)
entered into RCS
Diffstat (limited to 'pfinet/asm')
-rw-r--r--pfinet/asm/bitops.h135
1 files changed, 135 insertions, 0 deletions
diff --git a/pfinet/asm/bitops.h b/pfinet/asm/bitops.h
new file mode 100644
index 00000000..ee339bd6
--- /dev/null
+++ b/pfinet/asm/bitops.h
@@ -0,0 +1,135 @@
+#ifndef _I386_BITOPS_H
+#define _I386_BITOPS_H
+
+/*
+ * Copyright 1992, Linus Torvalds.
+ */
+
+/*
+ * These have to be done with inline assembly: that way the bit-setting
+ * is guaranteed to be atomic. All bit operations return 0 if the bit
+ * was cleared before the operation and != 0 if it was not.
+ *
+ * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
+ */
+
+/*
+ * Some hacks to defeat gcc over-optimizations..
+ */
+struct __dummy { unsigned long a[100]; };
+#define ADDR (*(struct __dummy *) addr)
+
+extern __inline__ int set_bit(int nr, void * addr)
+{
+ int oldbit;
+
+ __asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"r" (nr));
+ return oldbit;
+}
+
+extern __inline__ int clear_bit(int nr, void * addr)
+{
+ int oldbit;
+
+ __asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"r" (nr));
+ return oldbit;
+}
+
+extern __inline__ int change_bit(int nr, void * addr)
+{
+ int oldbit;
+
+ __asm__ __volatile__("btcl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"r" (nr));
+ return oldbit;
+}
+
+/*
+ * This routine doesn't need to be atomic, but it's faster to code it
+ * this way.
+ */
+extern __inline__ int test_bit(int nr, void * addr)
+{
+ int oldbit;
+
+ __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit)
+ :"m" (ADDR),"r" (nr));
+ return oldbit;
+}
+
+/*
+ * Find-bit routines..
+ */
+extern inline int find_first_zero_bit(void * addr, unsigned size)
+{
+ int res;
+
+ if (!size)
+ return 0;
+ __asm__("
+ cld
+ movl $-1,%%eax
+ repe; scasl
+ je 1f
+ subl $4,%%edi
+ movl (%%edi),%%eax
+ notl %%eax
+ bsfl %%eax,%%edx
+ jmp 2f
+1: xorl %%edx,%%edx
+2: subl %%ebx,%%edi
+ shll $3,%%edi
+ addl %%edi,%%edx"
+ :"=d" (res)
+ :"c" ((size + 31) >> 5), "D" (addr), "b" (addr)
+ :"ax", "bx", "cx", "di");
+ return res;
+}
+
+extern inline int find_next_zero_bit (void * addr, int size, int offset)
+{
+ unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
+ int set = 0, bit = offset & 31, res;
+
+ if (bit) {
+ /*
+ * Look for zero in first byte
+ */
+ __asm__("
+ bsfl %1,%0
+ jne 1f
+ movl $32, %0
+1: "
+ : "=r" (set)
+ : "r" (~(*p >> bit)));
+ if (set < (32 - bit))
+ return set + offset;
+ set = 32 - bit;
+ p++;
+ }
+ /*
+ * No zero yet, search remaining full bytes for a zero
+ */
+ res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
+ return (offset + set + res);
+}
+
+/*
+ * ffz = Find First Zero in word. Undefined if no zero exists,
+ * so code should check against ~0UL first..
+ */
+extern inline unsigned long ffz(unsigned long word)
+{
+ __asm__("bsfl %1,%0"
+ :"=r" (word)
+ :"r" (~word));
+ return word;
+}
+
+#endif /* _I386_BITOPS_H */