lib: utils: Drop dependency on libgcc by importing part of FreeBSD's libquad

We only need libgcc for 64-bit division on RV32. Whilst GCC toolchains
bundle libgcc, Clang toolchains tend not to ship libclang_rt.builtins
given every compiler is a cross-compiler for every target and so you
would need a silly number of builds of it, with only the native library
available; only vendor-provided Clang toolchains specifically for bare
metal cross-compiling are likely to provide it.

Thus, import part of FreeBSD's implementation of the division support
functions needed and stop linking against libgcc.

Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Anup Patel <anup.patel@wdc.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/lib/utils/libquad/quad.h b/lib/utils/libquad/quad.h
new file mode 100644
index 0000000..a9f8447
--- /dev/null
+++ b/lib/utils/libquad/quad.h
@@ -0,0 +1,105 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)quad.h	8.1 (Berkeley) 6/4/93
+ * $FreeBSD$
+ */
+
+/*
+ * Quad arithmetic.
+ *
+ * This library makes the following assumptions:
+ *
+ *  - The type long long (aka quad_t) exists.
+ *
+ *  - A quad variable is exactly twice as long as `long'.
+ *
+ *  - The machine's arithmetic is two's complement.
+ *
+ * This library can provide 128-bit arithmetic on a machine with 128-bit
+ * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
+ * with 48-bit longs.
+ */
+
+#include <sys/types.h>
+#include <limits.h>
+
+/*
+ * Depending on the desired operation, we view a `long long' (aka quad_t) in
+ * one or more of the following formats.
+ */
+union uu {
+	quad_t	q;		/* as a (signed) quad */
+	quad_t	uq;		/* as an unsigned quad */
+	long	sl[2];		/* as two signed longs */
+	u_long	ul[2];		/* as two unsigned longs */
+};
+
+/*
+ * Define high and low longwords.
+ */
+#define	H		_QUAD_HIGHWORD
+#define	L		_QUAD_LOWWORD
+
+/*
+ * Total number of bits in a quad_t and in the pieces that make it up.
+ * These are used for shifting, and also below for halfword extraction
+ * and assembly.
+ */
+#define	QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
+#define	LONG_BITS	(sizeof(long) * CHAR_BIT)
+#define	HALF_BITS	(sizeof(long) * CHAR_BIT / 2)
+
+/*
+ * Extract high and low shortwords from longword, and move low shortword of
+ * longword to upper half of long, i.e., produce the upper longword of
+ * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
+ *
+ * These are used in the multiply code, to split a longword into upper
+ * and lower halves, and to reassemble a product as a quad_t, shifted left
+ * (sizeof(long)*CHAR_BIT/2).
+ */
+#define	HHALF(x)	((x) >> HALF_BITS)
+#define	LHALF(x)	((x) & ((1L << HALF_BITS) - 1))
+#define	LHUP(x)		((x) << HALF_BITS)
+
+int		__cmpdi2(quad_t a, quad_t b);
+quad_t		__divdi3(quad_t a, quad_t b);
+quad_t		__moddi3(quad_t a, quad_t b);
+u_quad_t	__qdivrem(u_quad_t u, u_quad_t v, u_quad_t *rem);
+int		__ucmpdi2(u_quad_t a, u_quad_t b);
+u_quad_t	__udivdi3(u_quad_t a, u_quad_t b);
+u_quad_t	__umoddi3(u_quad_t a, u_quad_t b);
+
+typedef unsigned int	qshift_t;