1 files changed, 100 insertions, 0 deletions
diff --git a/contrib/lua-torch/torch7/lib/TH/THHalf.c b/contrib/lua-torch/torch7/lib/TH/THHalf.c
new file mode 100644
index 000000000..d7468ac3d
--- /dev/null
+++ b/contrib/lua-torch/torch7/lib/TH/THHalf.c
@@ -0,0 +1,100 @@
+#include "THHalf.h"
+
+/* Copyright 1993-2014 NVIDIA Corporation.  All rights reserved. */
+
+THHalf TH_float2half(float f)
+{
+  THHalf h;
+  TH_float2halfbits(&f, &h.x);
+  return h;
+}
+
+TH_API float TH_half2float(THHalf h)
+{
+  float f;
+  TH_halfbits2float(&h.x, &f);
+  return f;
+}
+
+// Host functions for converting between FP32 and FP16 formats
+
+void TH_halfbits2float(unsigned short* src, float* res)
+{
+    unsigned h = *src;
+    unsigned sign = ((h >> 15) & 1);
+    unsigned exponent = ((h >> 10) & 0x1f);
+    unsigned mantissa = ((h & 0x3ff) << 13);
+
+    if (exponent == 0x1f) {  /* NaN or Inf */
+        mantissa = (mantissa ? (sign = 0, 0x7fffff) : 0);
+        exponent = 0xff;
+    } else if (!exponent) {  /* Denorm or Zero */
+        if (mantissa) {
+            unsigned int msb;
+            exponent = 0x71;
+            do {
+                msb = (mantissa & 0x400000);
+                mantissa <<= 1;  /* normalize */
+                --exponent;
+            } while (!msb);
+            mantissa &= 0x7fffff;  /* 1.mantissa is implicit */
+        }
+    } else {
+        exponent += 0x70;
+    }
+
+    *(unsigned*)res = ((sign << 31) | (exponent << 23) | mantissa);
+}
+
+void TH_float2halfbits(float* src, unsigned short* dest)
+{
+    unsigned x = *(unsigned*)src;
+    unsigned u = (x & 0x7fffffff), remainder, shift, lsb, lsb_s1, lsb_m1;
+    unsigned sign, exponent, mantissa;
+
+    // Get rid of +NaN/-NaN case first.
+    if (u > 0x7f800000) {
+      *dest = 0x7fffU;
+      return ;
+    }
+
+    sign = ((x >> 16) & 0x8000);
+
+    // Get rid of +Inf/-Inf, +0/-0.
+    if (u > 0x477fefff) {
+      *dest = sign | 0x7c00U;
+      return;
+    }
+    if (u < 0x33000001) {
+      *dest = (sign | 0x0000);
+      return;
+    }
+
+    exponent = ((u >> 23) & 0xff);
+    mantissa = (u & 0x7fffff);
+
+    if (exponent > 0x70) {
+        shift = 13;
+        exponent -= 0x70;
+    } else {
+        shift = 0x7e - exponent;
+        exponent = 0;
+        mantissa |= 0x800000;
+    }
+    lsb = (1 << shift);
+    lsb_s1 = (lsb >> 1);
+    lsb_m1 = (lsb - 1);
+
+    // Round to nearest even.
+    remainder = (mantissa & lsb_m1);
+    mantissa >>= shift;
+    if (remainder > lsb_s1 || (remainder == lsb_s1 && (mantissa & 0x1))) {
+        ++mantissa;
+        if (!(mantissa & 0x3ff)) {
+            ++exponent;
+            mantissa = 0;
+        }
+    }
+
+    *dest = (sign | (exponent << 10) | mantissa);
+}