1 files changed, 123 insertions, 0 deletions
diff --git a/lib/fp_lib.h b/lib/fp_lib.h
new file mode 100644
index 000000000..b3c010491
--- /dev/null
+++ b/lib/fp_lib.h
@@ -0,0 +1,123 @@
+// This file is a configuration header for soft-float routines in compiler-rt.
+// This file does not provide any part of the compiler-rt interface.
+
+// Assumes that float and double correspond to the IEEE-754 binary32 and
+// binary64 types, respectively.
+
+#ifndef FP_LIB_HEADER
+#define FP_LIB_HEADER
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <limits.h>
+
+#if defined SINGLE_PRECISION
+#if 0
+#pragma mark single definitions
+#endif
+
+typedef uint32_t rep_t;
+typedef int32_t srep_t;
+typedef float fp_t;
+#define REP_C UINT32_C
+#define significandBits 23
+
+static inline int rep_clz(rep_t a) {
+    return __builtin_clz(a);
+}
+
+#elif defined DOUBLE_PRECISION
+#if 0
+#pragma mark double definitions
+#endif
+
+typedef uint64_t rep_t;
+typedef int64_t srep_t;
+typedef double fp_t;
+#define REP_C UINT64_C
+#define significandBits 52
+
+static inline int rep_clz(rep_t a) {
+#if defined __LP64__
+    return __builtin_clzl(a);
+#else
+    if (a & REP_C(0xffffffff00000000))
+        return 32 + __builtin_clz(a >> 32);
+    else 
+        return __builtin_clz(a & REP_C(0xffffffff));
+#endif
+}
+
+#else
+#error Either SINGLE_PRECISION or DOUBLE_PRECISION must be defined.
+#endif
+
+#if 0
+#pragma mark -
+#pragma mark integer constants
+#endif
+
+#define typeWidth       (sizeof(rep_t)*CHAR_BIT)
+#define exponentBits    (typeWidth - significandBits - 1)
+#define maxExponent     ((1 << exponentBits) - 1)
+#define exponentBias    (maxExponent >> 1)
+
+#if 0
+#pragma mark -
+#pragma mark rep_t constants
+#endif
+
+#define implicitBit     (REP_C(1) << significandBits)
+#define significandMask (implicitBit - 1U)
+#define signBit         (REP_C(1) << (significandBits + exponentBits))
+#define absMask         (signBit - 1U)
+#define exponentMask    (absMask ^ significandMask)
+#define oneRep          ((rep_t)exponentBias << significandBits)
+#define infRep          exponentMask
+#define quietBit        (implicitBit >> 1)
+#define qnanRep         (exponentMask | quietBit)
+
+#if 0
+#pragma mark -
+#pragma mark generic functions
+#endif
+
+static inline rep_t toRep(fp_t x) {
+    const union { fp_t f; rep_t i; } rep = {.f = x};
+    return rep.i;
+}
+
+static inline fp_t fromRep(rep_t x) {
+    const union { fp_t f; rep_t i; } rep = {.i = x};
+    return rep.f;
+}
+
+static inline int normalize(rep_t *significand) {
+    const int shift = rep_clz(*significand) - rep_clz(implicitBit);
+    *significand <<= shift;
+    return 1 - shift;
+}
+
+static inline void wideLeftShift(rep_t *hi, rep_t *lo, int count) {
+    *hi = *hi << count | *lo >> (typeWidth - count);
+    *lo = *lo << count;
+}
+
+static inline void wideRightShiftWithSticky(rep_t *hi, rep_t *lo, int count) {
+    if (count < typeWidth) {
+        const bool sticky = *lo << (typeWidth - count);
+        *lo = *hi << (typeWidth - count) | *lo >> count | sticky;
+        *hi = *hi >> count;
+    }
+    else if (count < 2*typeWidth) {
+        const bool sticky = *hi << (2*typeWidth - count) | *lo;
+        *lo = *hi >> (count - typeWidth) | sticky;
+        *hi = 0;
+    } else {
+        const bool sticky = *hi | *lo;
+        *lo = sticky;
+        *hi = 0;
+    }
+}
+
+#endif // FP_LIB_HEADER