On Sep 23, 2008, at 11:28 PM, Liu Yu-B13201 wrote:


diff --git a/arch/powerpc/include/asm/sfp-machine.h
b/arch/powerpc/include/asm/sfp-machine.h
new file mode 100644
index 0000000..ced34f1
--- /dev/null
+++ b/arch/powerpc/include/asm/sfp-machine.h
@@ -0,0 +1,353 @@
+/* Machine-dependent software floating-point definitions.
PPC version.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/ or
+   modify it under the terms of the GNU Library General
Public License as
+ published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will
be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file
COPYING.LIB.  If
+   not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+   Actually, this is a PPC (32bit) version, written based on the
+   i386, sparc, and sparc64 versions, by me,
+   Peter Maydell ([EMAIL PROTECTED]).
+   Comments are by and large also mine, although they may be
inaccurate.
+
+   In picking out asm fragments I've gone with the lowest common
+   denominator, which also happens to be the hardware I have :->
+   That is, a SPARC without hardware multiply and divide.
+ */
+
+/* basic word size definitions */
+#define _FP_W_TYPE_SIZE                32
+#define _FP_W_TYPE             unsigned long
+#define _FP_WS_TYPE            signed long
+#define _FP_I_TYPE             long
+
+#define __ll_B                 ((UWtype) 1 <<
(W_TYPE_SIZE / 2))
+#define __ll_lowpart(t)                ((UWtype) (t) & (__ll_B - 1))
+#define __ll_highpart(t)       ((UWtype) (t) >> (W_TYPE_SIZE / 2))
+
+/* You can optionally code some things like addition in asm. For
+ * example, i386 defines __FP_FRAC_ADD_2 as asm. If you don't
+ * then you get a fragment of C code [if you change an #ifdef 0
+ * in op-2.h] or a call to add_ssaaaa (see below).
+ * Good places to look for asm fragments to use are gcc and glibc.
+ * gcc's longlong.h is useful.
+ */
+
+/* We need to know how to multiply and divide. If the host word size
+ * is >= 2*fracbits you can use FP_MUL_MEAT_n_imm(t,R,X,Y) which
+ * codes the multiply with whatever gcc does to 'a * b'.
+ * _FP_MUL_MEAT_n_wide(t,R,X,Y,f) is used when you have an asm
+ * function that can multiply two 1W values and get a 2W result.
+ * Otherwise you're stuck with _FP_MUL_MEAT_n_hard(t,R,X,Y) which
+ * does bitshifting to avoid overflow.
+ * For division there is FP_DIV_MEAT_n_imm(t,R,X,Y,f) for word size
+ * >= 2*fracbits, where f is either _FP_DIV_HELP_imm or
+ * _FP_DIV_HELP_ldiv (see op-1.h).
+ * _FP_DIV_MEAT_udiv() is if you have asm to do 2W/1W => (1W, 1W).
+ * [GCC and glibc have longlong.h which has the asm macro udiv_qrnnd
+ * to do this.]
+ * In general, 'n' is the number of words required to hold the type,
+ * and 't' is either S, D or Q for single/double/quad.
+ *           -- PMM
+ */
+/* Example: SPARC64:
+ * #define _FP_MUL_MEAT_S(R,X,Y)       _FP_MUL_MEAT_1_imm(S,R,X,Y)
+ * #define _FP_MUL_MEAT_D(R,X,Y)       
_FP_MUL_MEAT_1_wide(D,R,X,Y,umul_ppmm)
+ * #define _FP_MUL_MEAT_Q(R,X,Y)       
_FP_MUL_MEAT_2_wide(Q,R,X,Y,umul_ppmm)
+ *
+ * #define _FP_DIV_MEAT_S(R,X,Y)       
_FP_DIV_MEAT_1_imm(S,R,X,Y,_FP_DIV_HELP_imm)
+ * #define _FP_DIV_MEAT_D(R,X,Y)       _FP_DIV_MEAT_1_udiv(D,R,X,Y)
+ * #define _FP_DIV_MEAT_Q(R,X,Y)       _FP_DIV_MEAT_2_udiv_64(Q,R,X,Y)
+ *
+ * Example: i386:
+ * #define _FP_MUL_MEAT_S(R,X,Y)
_FP_MUL_MEAT_1_wide(S,R,X,Y,_i386_mul_32_64)
+ * #define _FP_MUL_MEAT_D(R,X,Y)
_FP_MUL_MEAT_2_wide(D,R,X,Y,_i386_mul_32_64)
+ *
+ * #define _FP_DIV_MEAT_S(R,X,Y)
_FP_DIV_MEAT_1_udiv(S,R,X,Y,_i386_div_64_32)
+ * #define _FP_DIV_MEAT_D(R,X,Y)   _FP_DIV_MEAT_2_udiv_64(D,R,X,Y)
+ */
+
+#define _FP_MUL_MEAT_S(R,X,Y)
_FP_MUL_MEAT_1_wide(_FP_WFRACBITS_S,R,X,Y,umul_ppmm)
+#define _FP_MUL_MEAT_D(R,X,Y)
_FP_MUL_MEAT_2_wide(_FP_WFRACBITS_D,R,X,Y,umul_ppmm)
+
+#define _FP_DIV_MEAT_S(R,X,Y)  _FP_DIV_MEAT_1_udiv(S,R,X,Y)

It seems _FP_DIV_MEAT_S() should be defined to
_FP_DIV_MEAT_1_udiv_norm().
I can't remember very clear, but it seems single point float need to be
normalized before calling udiv_qrnnd.

For now I'm leaving as it was in the old code. We can submit fixes on top of this patch.

- k

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