Fix #107: Float input "1.000000" hit an edge case in the code that caused

the rounding increment at the end of float conversion to wrap the mantissa
from all 1's to 0, resulting in an incorrect result.

svn path=/trunk/yasm/; revision=1836

diff --git a/libyasm/floatnum.c b/libyasm/floatnum.c
index ac34352839667ef9be12fcb236bde3f39e095dcd..cb0435fe7710d65ac577b87a16a90b5261f48730 100644 (file)
--- a/libyasm/floatnum.c
+++ b/libyasm/floatnum.c
@@ -482,8 +482,11 @@ yasm_floatnum_create(const char *str)
         }
     }
 
-    /* Round the result. (Don't round underflow or overflow). */
-    if ((flt->exponent != EXP_INF) && (flt->exponent != EXP_ZERO))
+    /* Round the result. (Don't round underflow or overflow).  Also don't
+     * increment if this would cause the mantissa to wrap.
+     */
+    if ((flt->exponent != EXP_INF) && (flt->exponent != EXP_ZERO) &&
+        !BitVector_is_full(flt->mantissa))
         BitVector_increment(flt->mantissa);
 
     return flt;

diff --git a/libyasm/tests/floatnum_test.c b/libyasm/tests/floatnum_test.c
index 45f951df6cba257d548f8ead0f467cb5895d2281..907aac9859f3e4ce020066d1dbbff3e4aff4844a 100644 (file)
--- a/libyasm/tests/floatnum_test.c
+++ b/libyasm/tests/floatnum_test.c
@@ -95,6 +95,19 @@ static Init_Entry normalized_vals[] = {
          0, {0x00,0x00,0x00,0x00,0x00,0xf4,0xb6,0xc0},
          0, {0x00,0x00,0x00,0x00,0x00,0x00,0xa0,0xb7,0x0b,0xc0}
     },
+    /* Edge cases for rounding wrap. */
+    {   "1.00000",
+        {0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff},0x7ffe,0,0,
+         0, {0x00,0x00,0x80,0x3f},
+         0, {0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f},
+         0, {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0xff,0x3f}
+    },
+    {   "1.000000",
+        {0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff},0x7ffe,0,0,
+         0, {0x00,0x00,0x80,0x3f},
+         0, {0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f},
+         0, {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0xff,0x3f}
+    },
 };
 
 /* Still normalized values, but edge cases of various sizes, testing underflow/
@@ -417,7 +430,8 @@ runtest_(const char *testname, int (*testfunc)(void), void (*setup)(void),
     printf("%c", nf>0 ? 'F':'.');
     fflush(stdout);
     if (nf > 0)
-        sprintf(failed, "%s ** F: %s failed!\n", failed, testname);
+        sprintf(failed, "%s ** F: %s failed: %s!\n", failed, testname,
+                result_msg);
     return nf;
 }
 #define runtest(x,y,z)  runtest_(#x,test_##x,y,z)