Changeset 84929b0 in mainline for uspace/lib/math/generic/trunc.c

Timestamp:

2018-08-29T20:06:00Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Children:

ed9043f7

Parents:

184ff675

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-08-29 19:44:33)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-08-29 20:06:00)

Message:

Strip libmath to the bare necessities

File:

• uspace/lib/math/generic/trunc.c (modified) (3 diffs)

uspace/lib/math/generic/trunc.c

@@ -34 +34 @@
  */
 
-#include <mathtypes.h>
-#include <trunc.h>
+#include <math.h>
+#include <float.h>
+#include <stdint.h>
 
 /** Truncate fractional part (round towards zero)
@@ -52 +53 @@
  *
  */
-float32_t float32_trunc(float32_t val)
+float truncf(float val)
 {
-        float32_u v;
-        int32_t exp;
+        /* If the input is a nan, return a canonical nan. */
+        if (isnan(val))
+                return __builtin_nanf("");
 
-        v.val = val;
-        exp = v.data.parts.exp - FLOAT32_BIAS;
+        const int exp_bias = FLT_MAX_EXP - 1;
+        const int mant_bits = FLT_MANT_DIG - 1;
+        const uint32_t mant_mask = (UINT32_C(1) << mant_bits) - 1;
 
-        if (exp < 0) {
-                /* -1 < val < 1 => result is +0 or -0 */
-                v.data.parts.exp = 0;
-                v.data.parts.fraction = 0;
-        } else if (exp >= FLOAT32_FRACTION_SIZE) {
-                if (exp == 1024) {
-                        /* val is +inf, -inf or NaN => trigger an exception */
-                        // FIXME TODO
-                }
+        union {
+                float f;
+                uint32_t i;
+        } u = { .f = fabsf(val) };
 
-                /* All bits in val are relevant for the result */
-        } else {
-                /* Truncate irrelevant fraction bits */
-                v.data.parts.fraction &= ~(UINT32_C(0x007fffff) >> exp);
-        }
+        int exp = (u.i >> mant_bits) - exp_bias;
 
-        return v.val;
+        /* If value is less than one, return zero with appropriate sign. */
+        if (exp < 0)
+                return copysignf(0.0f, val);
+
+        if (exp >= mant_bits)
+                return val;
+
+        /* Truncate irrelevant fraction bits */
+        u.i &= ~(mant_mask >> exp);
+        return copysignf(u.f, val);
 }
 
@@ -94 +97 @@
  *
  */
-float64_t float64_trunc(float64_t val)
+double trunc(double val)
 {
-        float64_u v;
-        int32_t exp;
+        /* If the input is a nan, return a canonical nan. */
+        if (isnan(val))
+                return __builtin_nan("");
 
-        v.val = val;
-        exp = v.data.parts.exp - FLOAT64_BIAS;
+        const int exp_bias = DBL_MAX_EXP - 1;
+        const int mant_bits = DBL_MANT_DIG - 1;
+        const uint64_t mant_mask = (UINT64_C(1) << mant_bits) - 1;
 
-        if (exp < 0) {
-                /* -1 < val < 1 => result is +0 or -0 */
-                v.data.parts.exp = 0;
-                v.data.parts.fraction = 0;
-        } else if (exp >= FLOAT64_FRACTION_SIZE) {
-                if (exp == 1024) {
-                        /* val is +inf, -inf or NaN => trigger an exception */
-                        // FIXME TODO
-                }
+        union {
+                double f;
+                uint64_t i;
+        } u = { .f = fabs(val) };
 
-                /* All bits in val are relevant for the result */
-        } else {
-                /* Truncate irrelevant fraction bits */
-                v.data.parts.fraction &= ~(UINT64_C(0x000fffffffffffff) >> exp);
-        }
+        int exp = ((int)(u.i >> mant_bits)) - exp_bias;
 
-        return v.val;
+        /* If value is less than one, return zero with appropriate sign. */
+        if (exp < 0)
+                return copysign(0.0, val);
+
+        if (exp >= mant_bits)
+                return val;
+
+        /* Truncate irrelevant fraction bits */
+        u.i &= ~(mant_mask >> exp);
+        return copysign(u.f, val);
 }