GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/arch/x86/lib/div64.c

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+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * This file is copied from the coreboot repository as part of
+ * the libpayload project:
+ *
+ * Copyright 2014 Google Inc.
+ */
+
+#include <common.h>
+
+union overlay64 {
+	u64 longw;
+	struct {
+		u32 lower;
+		u32 higher;
+	} words;
+};
+
+u64 __ashldi3(u64 num, unsigned int shift)
+{
+	union overlay64 output;
+
+	output.longw = num;
+	if (shift >= 32) {
+		output.words.higher = output.words.lower << (shift - 32);
+		output.words.lower = 0;
+	} else {
+		if (!shift)
+			return num;
+		output.words.higher = (output.words.higher << shift) |
+			(output.words.lower >> (32 - shift));
+		output.words.lower = output.words.lower << shift;
+	}
+	return output.longw;
+}
+
+u64 __lshrdi3(u64 num, unsigned int shift)
+{
+	union overlay64 output;
+
+	output.longw = num;
+	if (shift >= 32) {
+		output.words.lower = output.words.higher >> (shift - 32);
+		output.words.higher = 0;
+	} else {
+		if (!shift)
+			return num;
+		output.words.lower = output.words.lower >> shift |
+			(output.words.higher << (32 - shift));
+		output.words.higher = output.words.higher >> shift;
+	}
+	return output.longw;
+}
+
+#define MAX_32BIT_UINT ((((u64)1) << 32) - 1)
+
+static u64 _64bit_divide(u64 dividend, u64 divider, u64 *rem_p)
+{
+	u64 result = 0;
+
+	/*
+	 * If divider is zero - let the rest of the system care about the
+	 * exception.
+	 */
+	if (!divider)
+		return 1 / (u32)divider;
+
+	/* As an optimization, let's not use 64 bit division unless we must. */
+	if (dividend <= MAX_32BIT_UINT) {
+		if (divider > MAX_32BIT_UINT) {
+			result = 0;
+			if (rem_p)
+				*rem_p = divider;
+		} else {
+			result = (u32)dividend / (u32)divider;
+			if (rem_p)
+				*rem_p = (u32)dividend % (u32)divider;
+		}
+		return result;
+	}
+
+	while (divider <= dividend) {
+		u64 locald = divider;
+		u64 limit = __lshrdi3(dividend, 1);
+		int shifts = 0;
+
+		while (locald <= limit) {
+			shifts++;
+			locald = locald + locald;
+		}
+		result |= __ashldi3(1, shifts);
+		dividend -= locald;
+	}
+
+	if (rem_p)
+		*rem_p = dividend;
+
+	return result;
+}
+
+u64 __udivdi3(u64 num, u64 den)
+{
+	return _64bit_divide(num, den, NULL);
+}
+
+u64 __umoddi3(u64 num, u64 den)
+{
+	u64 v = 0;
+
+	_64bit_divide(num, den, &v);
+	return v;
+}