summaryrefslogtreecommitdiffstats
path: root/arch/ia64/lib/idiv32.S
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ia64/lib/idiv32.S
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/ia64/lib/idiv32.S')
-rw-r--r--arch/ia64/lib/idiv32.S83
1 files changed, 83 insertions, 0 deletions
diff --git a/arch/ia64/lib/idiv32.S b/arch/ia64/lib/idiv32.S
new file mode 100644
index 00000000000..2ac28bf0a66
--- /dev/null
+++ b/arch/ia64/lib/idiv32.S
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2000 Hewlett-Packard Co
+ * Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * 32-bit integer division.
+ *
+ * This code is based on the application note entitled "Divide, Square Root
+ * and Remainder Algorithms for the IA-64 Architecture". This document
+ * is available as Intel document number 248725-002 or via the web at
+ * http://developer.intel.com/software/opensource/numerics/
+ *
+ * For more details on the theory behind these algorithms, see "IA-64
+ * and Elementary Functions" by Peter Markstein; HP Professional Books
+ * (http://www.hp.com/go/retailbooks/)
+ */
+
+#include <asm/asmmacro.h>
+
+#ifdef MODULO
+# define OP mod
+#else
+# define OP div
+#endif
+
+#ifdef UNSIGNED
+# define SGN u
+# define EXTEND zxt4
+# define INT_TO_FP(a,b) fcvt.xuf.s1 a=b
+# define FP_TO_INT(a,b) fcvt.fxu.trunc.s1 a=b
+#else
+# define SGN
+# define EXTEND sxt4
+# define INT_TO_FP(a,b) fcvt.xf a=b
+# define FP_TO_INT(a,b) fcvt.fx.trunc.s1 a=b
+#endif
+
+#define PASTE1(a,b) a##b
+#define PASTE(a,b) PASTE1(a,b)
+#define NAME PASTE(PASTE(__,SGN),PASTE(OP,si3))
+
+GLOBAL_ENTRY(NAME)
+ .regstk 2,0,0,0
+ // Transfer inputs to FP registers.
+ mov r2 = 0xffdd // r2 = -34 + 65535 (fp reg format bias)
+ EXTEND in0 = in0 // in0 = a
+ EXTEND in1 = in1 // in1 = b
+ ;;
+ setf.sig f8 = in0
+ setf.sig f9 = in1
+#ifdef MODULO
+ sub in1 = r0, in1 // in1 = -b
+#endif
+ ;;
+ // Convert the inputs to FP, to avoid FP software-assist faults.
+ INT_TO_FP(f8, f8)
+ INT_TO_FP(f9, f9)
+ ;;
+ setf.exp f7 = r2 // f7 = 2^-34
+ frcpa.s1 f6, p6 = f8, f9 // y0 = frcpa(b)
+ ;;
+(p6) fmpy.s1 f8 = f8, f6 // q0 = a*y0
+(p6) fnma.s1 f6 = f9, f6, f1 // e0 = -b*y0 + 1
+ ;;
+#ifdef MODULO
+ setf.sig f9 = in1 // f9 = -b
+#endif
+(p6) fma.s1 f8 = f6, f8, f8 // q1 = e0*q0 + q0
+(p6) fma.s1 f6 = f6, f6, f7 // e1 = e0*e0 + 2^-34
+ ;;
+#ifdef MODULO
+ setf.sig f7 = in0
+#endif
+(p6) fma.s1 f6 = f6, f8, f8 // q2 = e1*q1 + q1
+ ;;
+ FP_TO_INT(f6, f6) // q = trunc(q2)
+ ;;
+#ifdef MODULO
+ xma.l f6 = f6, f9, f7 // r = q*(-b) + a
+ ;;
+#endif
+ getf.sig r8 = f6 // transfer result to result register
+ br.ret.sptk.many rp
+END(NAME)