Adding soft-float comparisons, addition, subtraction, multiplication and negation

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@107400 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 127 insertions, 0 deletions

diff --git a/lib/comparedf2.c b/lib/comparedf2.c
new file mode 100644
index 00000000..de700808
--- /dev/null
+++ b/lib/comparedf2.c
@@ -0,0 +1,127 @@
+/*
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is distributed under the University of Illinois Open Source
+ * License. See LICENSE.TXT for details.
+ */
+
+#define DOUBLE_PRECISION
+#include "fp_lib.h"
+
+// This file implements the following soft-float comparison routines:
+//
+//   __eqdf2   __gedf2   __nedf2
+//   __ledf2   __gtdf2
+//   __ltdf2
+//   __nedf2
+//
+// The semantics of the routines grouped in each column are identical, so there
+// is a single implementation for each, and wrappers to provide the other names.
+//
+// The main routines behave as follows:
+//
+//   __ledf2(a,b) returns -1 if a < b
+//                         0 if a == b
+//                         1 if a > b
+//                         1 if either a or b is NaN
+//
+//   __gedf2(a,b) returns -1 if a < b
+//                         0 if a == b
+//                         1 if a > b
+//                        -1 if either a or b is NaN
+//
+//   __unorddf2(a,b) returns 0 if both a and b are numbers
+//                           1 if either a or b is NaN
+//
+// Note that __ledf2( ) and __gedf2( ) are identical except in their handling of
+// NaN values.
+
+enum LE_RESULT {
+    LE_LESS      = -1,
+    LE_EQUAL     =  0,
+    LE_GREATER   =  1,
+    LE_UNORDERED =  1
+};
+
+enum LE_RESULT __ledf2(fp_t a, fp_t b) {
+    
+    const srep_t aInt = toRep(a);
+    const srep_t bInt = toRep(b);
+    const rep_t aAbs = aInt & absMask;
+    const rep_t bAbs = bInt & absMask;
+    
+    // If either a or b is NaN, they are unordered.
+    if (aAbs > infRep || bAbs > infRep) return LE_UNORDERED;
+    
+    // If a and b are both zeros, they are equal.
+    if ((aAbs | bAbs) == 0) return LE_EQUAL;
+    
+    // If at least one of a and b is positive, we get the same result comparing
+    // a and b as signed integers as we would with a floating-point compare.
+    if ((aInt & bInt) >= 0) {
+        if (aInt < bInt) return LE_LESS;
+        else if (aInt == bInt) return LE_EQUAL;
+        else return LE_GREATER;
+    }
+    
+    // Otherwise, both are negative, so we need to flip the sense of the
+    // comparison to get the correct result.  (This assumes a twos- or ones-
+    // complement integer representation; if integers are represented in a
+    // sign-magnitude representation, then this flip is incorrect).
+    else {
+        if (aInt > bInt) return LE_LESS;
+        else if (aInt == bInt) return LE_EQUAL;
+        else return LE_GREATER;
+    }
+}
+
+
+enum GE_RESULT {
+    GE_LESS      = -1,
+    GE_EQUAL     =  0,
+    GE_GREATER   =  1,
+    GE_UNORDERED = -1   // Note: different from LE_UNORDERED
+};
+
+enum GE_RESULT __gedf2(fp_t a, fp_t b) {
+    
+    const srep_t aInt = toRep(a);
+    const srep_t bInt = toRep(b);
+    const rep_t aAbs = aInt & absMask;
+    const rep_t bAbs = bInt & absMask;
+    
+    if (aAbs > infRep || bAbs > infRep) return GE_UNORDERED;
+    if ((aAbs | bAbs) == 0) return GE_EQUAL;
+    if ((aInt & bInt) >= 0) {
+        if (aInt < bInt) return GE_LESS;
+        else if (aInt == bInt) return GE_EQUAL;
+        else return GE_GREATER;
+    } else {
+        if (aInt > bInt) return GE_LESS;
+        else if (aInt == bInt) return GE_EQUAL;
+        else return GE_GREATER;
+    }
+}
+
+int __unorddf2(fp_t a, fp_t b) {
+    const rep_t aAbs = toRep(a) & absMask;
+    const rep_t bAbs = toRep(b) & absMask;
+    return aAbs > infRep || bAbs > infRep;
+}
+
+enum LE_RESULT __eqdf2(fp_t a, fp_t b) {
+    return __ledf2(a, b);
+}
+
+enum LE_RESULT __ltdf2(fp_t a, fp_t b) {
+    return __ledf2(a, b);
+}
+
+enum LE_RESULT __nedf2(fp_t a, fp_t b) {
+    return __ledf2(a, b);
+}
+
+enum GE_RESULT __gtdf2(fp_t a, fp_t b) {
+    return __gedf2(a, b);
+}
+