initial version

Book-Lite/linux-0.12/kernel/math/mul.c

@@ -0,0 +1,73 @@
+/*
+ * linux/kernel/math/mul.c
+ *
+ * (C) 1991 Linus Torvalds
+ */
+
+/*
+ * temporary real multiplication routine.
+ */
+
+#include <linux/math_emu.h>
+
+static void shift(int * c)
+{
+	__asm__("movl (%0),%%eax ; addl %%eax,(%0)\n\t"
+		"movl 4(%0),%%eax ; adcl %%eax,4(%0)\n\t"
+		"movl 8(%0),%%eax ; adcl %%eax,8(%0)\n\t"
+		"movl 12(%0),%%eax ; adcl %%eax,12(%0)"
+		::"r" ((long) c):"ax");
+}
+
+static void mul64(const temp_real * a, const temp_real * b, int * c)
+{
+	__asm__("movl (%0),%%eax\n\t"
+		"mull (%1)\n\t"
+		"movl %%eax,(%2)\n\t"
+		"movl %%edx,4(%2)\n\t"
+		"movl 4(%0),%%eax\n\t"
+		"mull 4(%1)\n\t"
+		"movl %%eax,8(%2)\n\t"
+		"movl %%edx,12(%2)\n\t"
+		"movl (%0),%%eax\n\t"
+		"mull 4(%1)\n\t"
+		"addl %%eax,4(%2)\n\t"
+		"adcl %%edx,8(%2)\n\t"
+		"adcl $0,12(%2)\n\t"
+		"movl 4(%0),%%eax\n\t"
+		"mull (%1)\n\t"
+		"addl %%eax,4(%2)\n\t"
+		"adcl %%edx,8(%2)\n\t"
+		"adcl $0,12(%2)"
+		::"b" ((long) a),"c" ((long) b),"D" ((long) c)
+		:"ax","dx");
+}
+
+void fmul(const temp_real * src1, const temp_real * src2, temp_real * result)
+{
+	int i,sign;
+	int tmp[4] = {0,0,0,0};
+
+	sign = (src1->exponent ^ src2->exponent) & 0x8000;
+	i = (src1->exponent & 0x7fff) + (src2->exponent & 0x7fff) - 16383 + 1;
+	if (i<0) {
+		result->exponent = sign;
+		result->a = result->b = 0;
+		return;
+	}
+	if (i>0x7fff) {
+		set_OE();
+		return;
+	}
+	mul64(src1,src2,tmp);
+	if (tmp[0] || tmp[1] || tmp[2] || tmp[3])
+		while (i && tmp[3] >= 0) {
+			i--;
+			shift(tmp);
+		}
+	else
+		i = 0;
+	result->exponent = i | sign;
+	result->a = tmp[2];
+	result->b = tmp[3];
+}