From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/m68k/math-emu/fp_log.c | 219 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 219 insertions(+)
 create mode 100644 arch/m68k/math-emu/fp_log.c

(limited to 'arch/m68k/math-emu/fp_log.c')

diff --git a/arch/m68k/math-emu/fp_log.c b/arch/m68k/math-emu/fp_log.c
new file mode 100644
index 000000000..066306787
--- /dev/null
+++ b/arch/m68k/math-emu/fp_log.c
@@ -0,0 +1,219 @@
+/*
+
+  fp_trig.c: floating-point math routines for the Linux-m68k
+  floating point emulator.
+
+  Copyright (c) 1998-1999 David Huggins-Daines / Roman Zippel.
+
+  I hereby give permission, free of charge, to copy, modify, and
+  redistribute this software, in source or binary form, provided that
+  the above copyright notice and the following disclaimer are included
+  in all such copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS", WITH ABSOLUTELY NO WARRANTY, REAL
+  OR IMPLIED.
+
+*/
+
+#include "fp_emu.h"
+
+static const struct fp_ext fp_one =
+{
+	.exp = 0x3fff,
+};
+
+extern struct fp_ext *fp_fadd(struct fp_ext *dest, const struct fp_ext *src);
+extern struct fp_ext *fp_fdiv(struct fp_ext *dest, const struct fp_ext *src);
+
+struct fp_ext *
+fp_fsqrt(struct fp_ext *dest, struct fp_ext *src)
+{
+	struct fp_ext tmp, src2;
+	int i, exp;
+
+	dprint(PINSTR, "fsqrt\n");
+
+	fp_monadic_check(dest, src);
+
+	if (IS_ZERO(dest))
+		return dest;
+
+	if (dest->sign) {
+		fp_set_nan(dest);
+		return dest;
+	}
+	if (IS_INF(dest))
+		return dest;
+
+	/*
+	 *		 sqrt(m) * 2^(p)	, if e = 2*p
+	 * sqrt(m*2^e) =
+	 *		 sqrt(2*m) * 2^(p)	, if e = 2*p + 1
+	 *
+	 * So we use the last bit of the exponent to decide whether to
+	 * use the m or 2*m.
+	 *
+	 * Since only the fractional part of the mantissa is stored and
+	 * the integer part is assumed to be one, we place a 1 or 2 into
+	 * the fixed point representation.
+	 */
+	exp = dest->exp;
+	dest->exp = 0x3FFF;
+	if (!(exp & 1))		/* lowest bit of exponent is set */
+		dest->exp++;
+	fp_copy_ext(&src2, dest);
+
+	/*
+	 * The taylor row around a for sqrt(x) is:
+	 *	sqrt(x) = sqrt(a) + 1/(2*sqrt(a))*(x-a) + R
+	 * With a=1 this gives:
+	 *	sqrt(x) = 1 + 1/2*(x-1)
+	 *		= 1/2*(1+x)
+	 */
+	fp_fadd(dest, &fp_one);
+	dest->exp--;		/* * 1/2 */
+
+	/*
+	 * We now apply the newton rule to the function
+	 *	f(x) := x^2 - r
+	 * which has a null point on x = sqrt(r).
+	 *
+	 * It gives:
+	 *	x' := x - f(x)/f'(x)
+	 *	    = x - (x^2 -r)/(2*x)
+	 *	    = x - (x - r/x)/2
+	 *          = (2*x - x + r/x)/2
+	 *	    = (x + r/x)/2
+	 */
+	for (i = 0; i < 9; i++) {
+		fp_copy_ext(&tmp, &src2);
+
+		fp_fdiv(&tmp, dest);
+		fp_fadd(dest, &tmp);
+		dest->exp--;
+	}
+
+	dest->exp += (exp - 0x3FFF) / 2;
+
+	return dest;
+}
+
+struct fp_ext *
+fp_fetoxm1(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("fetoxm1\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_fetox(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("fetox\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_ftwotox(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("ftwotox\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_ftentox(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("ftentox\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_flogn(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("flogn\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_flognp1(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("flognp1\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_flog10(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("flog10\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_flog2(struct fp_ext *dest, struct fp_ext *src)
+{
+	uprint("flog2\n");
+
+	fp_monadic_check(dest, src);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_fgetexp(struct fp_ext *dest, struct fp_ext *src)
+{
+	dprint(PINSTR, "fgetexp\n");
+
+	fp_monadic_check(dest, src);
+
+	if (IS_INF(dest)) {
+		fp_set_nan(dest);
+		return dest;
+	}
+	if (IS_ZERO(dest))
+		return dest;
+
+	fp_conv_long2ext(dest, (int)dest->exp - 0x3FFF);
+
+	fp_normalize_ext(dest);
+
+	return dest;
+}
+
+struct fp_ext *
+fp_fgetman(struct fp_ext *dest, struct fp_ext *src)
+{
+	dprint(PINSTR, "fgetman\n");
+
+	fp_monadic_check(dest, src);
+
+	if (IS_ZERO(dest))
+		return dest;
+
+	if (IS_INF(dest))
+		return dest;
+
+	dest->exp = 0x3FFF;
+
+	return dest;
+}
+
-- 
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