Changeset 992ffa6 in mainline for uspace/lib/math/generic/trunc.c

Timestamp:

2015-09-04T06:40:20Z (10 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

01cdd5a

Parents:

bae1e1f

Message:

Add exp(f), log(f), pow(f). Improve precision of sin, cos.

File:

• uspace/lib/math/generic/trunc.c (modified) (1 diff)

uspace/lib/math/generic/trunc.c

@@ -35 +35 @@
 #include <mathtypes.h>
 #include <trunc.h>
+
+/** Truncate fractional part (round towards zero)
+ *
+ * Truncate the fractional part of IEEE 754 single
+ * precision floating point number by zeroing fraction
+ * bits, effectively rounding the number towards zero
+ * to the nearest whole number.
+ *
+ * If the argument is infinity or NaN, an exception
+ * should be indicated. This is not implemented yet.
+ *
+ * @param val Floating point number.
+ *
+ * @return Number rounded towards zero.
+ *
+ */
+float32 trunc_float32(float32 val)
+{
+        int32_t exp = val.parts.exp - FLOAT32_BIAS;
+        
+        if (exp < 0) {
+                /* -1 < val < 1 => result is +0 or -0 */
+                val.parts.exp = 0;
+                val.parts.fraction = 0;
+        } else if (exp >= FLOAT32_FRACTION_SIZE) {
+                if (exp == 1024) {
+                        /* val is +inf, -inf or NaN => trigger an exception */
+                        // FIXME TODO
+                }
+                
+                /* All bits in val are relevant for the result */
+        } else {
+                /* Truncate irrelevant fraction bits */
+                val.parts.fraction &= ~(UINT32_C(0x007fffff) >> exp);
+        }
+        
+        return val;
+}
 
 /** Truncate fractional part (round towards zero)