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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-arm/div64.h
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Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'include/asm-arm/div64.h')
-rw-r--r--include/asm-arm/div64.h48
1 files changed, 48 insertions, 0 deletions
diff --git a/include/asm-arm/div64.h b/include/asm-arm/div64.h
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+++ b/include/asm-arm/div64.h
@@ -0,0 +1,48 @@
+#ifndef __ASM_ARM_DIV64
+#define __ASM_ARM_DIV64
+
+#include <asm/system.h>
+
+/*
+ * The semantics of do_div() are:
+ *
+ * uint32_t do_div(uint64_t *n, uint32_t base)
+ * {
+ * uint32_t remainder = *n % base;
+ * *n = *n / base;
+ * return remainder;
+ * }
+ *
+ * In other words, a 64-bit dividend with a 32-bit divisor producing
+ * a 64-bit result and a 32-bit remainder. To accomplish this optimally
+ * we call a special __do_div64 helper with completely non standard
+ * calling convention for arguments and results (beware).
+ */
+
+#ifdef __ARMEB__
+#define __xh "r0"
+#define __xl "r1"
+#else
+#define __xl "r0"
+#define __xh "r1"
+#endif
+
+#define do_div(n,base) \
+({ \
+ register unsigned int __base asm("r4") = base; \
+ register unsigned long long __n asm("r0") = n; \
+ register unsigned long long __res asm("r2"); \
+ register unsigned int __rem asm(__xh); \
+ asm( __asmeq("%0", __xh) \
+ __asmeq("%1", "r2") \
+ __asmeq("%2", "r0") \
+ __asmeq("%3", "r4") \
+ "bl __do_div64" \
+ : "=r" (__rem), "=r" (__res) \
+ : "r" (__n), "r" (__base) \
+ : "ip", "lr", "cc"); \
+ n = __res; \
+ __rem; \
+})
+
+#endif
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