From 166e5c7ee3e964d4a7ed1057e4511d8efe285f57 Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Thu, 6 Jan 2011 15:38:19 +0100 Subject: [PATCH] target-mips: Implement correct NaN propagation rules Implement the correct NaN propagation rules for MIPS targets by providing an appropriate pickNaN function. Signed-off-by: Aurelien Jarno --- fpu/softfloat-specialize.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h index 3ce5bb5..acdd299 100644 --- a/fpu/softfloat-specialize.h +++ b/fpu/softfloat-specialize.h @@ -192,6 +192,33 @@ static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN, return 1; } } +#elif defined(TARGET_MIPS) +static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN, + flag aIsLargerSignificand) +{ + /* According to MIPS specifications, if one of the two operands is + * a sNaN, a new qNaN has to be generated. This is done in + * floatXX_maybe_silence_nan(). For qNaN inputs the specifications + * says: "When possible, this QNaN result is one of the operand QNaN + * values." In practice it seems that most implementations choose + * the first operand if both operands are qNaN. In short this gives + * the following rules: + * 1. A if it is signaling + * 2. B if it is signaling + * 3. A (quiet) + * 4. B (quiet) + * A signaling NaN is always silenced before returning it. + */ + if (aIsSNaN) { + return 0; + } else if (bIsSNaN) { + return 1; + } else if (aIsQNaN) { + return 0; + } else { + return 1; + } +} #else static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN, flag aIsLargerSignificand) -- 2.7.4