fpu/softfloat: fix up float16 nan recognition

LIU Zhiwei · stsquad · commit 8cdf91243f75 · 2020-07-15T11:52:43.000+01:00
Signed-off-by: LIU Zhiwei &lt;zhiwei_liu@c-sky.com&gt;
Signed-off-by: Alex Bennée &lt;alex.bennee@linaro.org&gt;
Reviewed-by: Richard Henderson &lt;richard.henderson@linaro.org&gt;
Message-Id: &lt;20200712234521.3972-2-zhiwei_liu@c-sky.com&gt;
Message-Id: &lt;20200713200415.26214-5-alex.bennee@linaro.org&gt;
diff --git a/fpu/softfloat-specialize.inc.c b/fpu/softfloat-specialize.inc.c
@@ -254,7 +254,7 @@ bool float16_is_quiet_nan(float16 a_, float_status *status)
     if (snan_bit_is_one(status)) {
         return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);
     } else {
-        return ((a & ~0x8000) >= 0x7C80);
+        return ((a >> 9) & 0x3F) == 0x3F;
     }
 #endif
 }
@@ -271,7 +271,7 @@ bool float16_is_signaling_nan(float16 a_, float_status *status)
 #else
     uint16_t a = float16_val(a_);
     if (snan_bit_is_one(status)) {
-        return ((a & ~0x8000) >= 0x7C80);
+        return ((a >> 9) & 0x3F) == 0x3F;
     } else {
         return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);
     }

Original file line number	Diff line number	Diff line change
`@@ -254,7 +254,7 @@ bool float16_is_quiet_nan(float16 a_, float_status *status)`
`254`	`254`	`if (snan_bit_is_one(status)) {`
`255`	`255`	`return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);`
`256`	`256`	`} else {`
`257`		`- return ((a & ~0x8000) >= 0x7C80);`
	`257`	`+ return ((a >> 9) & 0x3F) == 0x3F;`
`258`	`258`	`}`
`259`	`259`	`#endif`
`260`	`260`	`}`
`@@ -271,7 +271,7 @@ bool float16_is_signaling_nan(float16 a_, float_status *status)`
`271`	`271`	`#else`
`272`	`272`	`uint16_t a = float16_val(a_);`
`273`	`273`	`if (snan_bit_is_one(status)) {`
`274`		`- return ((a & ~0x8000) >= 0x7C80);`
	`274`	`+ return ((a >> 9) & 0x3F) == 0x3F;`
`275`	`275`	`} else {`
`276`	`276`	`return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);`
`277`	`277`	`}`