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Diffstat (limited to 'openpcd/firmware/include/asm/div64.h')
-rw-r--r--openpcd/firmware/include/asm/div64.h48
1 files changed, 48 insertions, 0 deletions
diff --git a/openpcd/firmware/include/asm/div64.h b/openpcd/firmware/include/asm/div64.h
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+++ b/openpcd/firmware/include/asm/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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