correctly handle special case of lowest negative number like -0x80 or…

… -0x8000 this is correctly representable as negative integer and should not raise #IE
bochs-emu · Nov 13, 2024 · 949eb11 · 949eb11
1 parent 3ee35f1
commit 949eb11
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Showing 3 changed files with 8 additions and 3 deletions.
diff --git a/bochs/cpu/softfloat3e/f16_to_i16.c b/bochs/cpu/softfloat3e/f16_to_i16.c
@@ -76,6 +76,7 @@ int16_t f16_to_i16(float16 a, uint8_t roundingMode, bool exact, struct softfloat
     if (0 <= shiftDist) {
         sig32 <<= shiftDist;
         if (shiftDist > 4) {
+            if (a == packToF16UI(1, 0x1E, 0)) return -0x7FFF - 1;
             softfloat_raiseFlags(status, softfloat_flag_invalid);
             return sign ? i16_fromNegOverflow : i16_fromPosOverflow;
         }

diff --git a/bochs/cpu/softfloat3e/f16_to_i8.c b/bochs/cpu/softfloat3e/f16_to_i8.c
@@ -61,8 +61,6 @@ int8_t f16_to_i8(float16 a, uint8_t roundingMode, bool exact, bool saturate, str
     *------------------------------------------------------------------------*/
     shiftDist = 0x16 - exp;
     if (shiftDist < 0) {
-        if (a == packToF16UI(1, 0x16, 0)) return -0x7F - 1;
-
         const int8_t NegOverflowResponse = saturate ? i8_minNegativeValue : i8_fromNegOverflow;
         const int8_t PosOverflowResponse = saturate ? i8_maxPositiveValue : i8_fromPosOverflow;
 

diff --git a/bochs/cpu/softfloat3e/f16_to_i8_r_minMag.c b/bochs/cpu/softfloat3e/f16_to_i8_r_minMag.c
@@ -64,7 +64,13 @@ int8_t f16_to_i8_r_minMag(float16 a, bool exact, bool saturate, struct softfloat
     *------------------------------------------------------------------------*/
     shiftDist = 0x19 - exp;
     if (shiftDist <= 3) {
-        if (a == packToF16UI(1, 0x16, 0)) return -0x7F - 1;
+        if (shiftDist == 3) {
+            uint16_t roundMask = a & 0x7;
+            if ((a & ~roundMask) == packToF16UI(1, 0x16, 0)) {
+                if (roundMask) softfloat_raiseFlags(status, softfloat_flag_inexact);
+                return -0x7F - 1;
+            }
+        }
 
         const int8_t NaN_response = saturate ? 0 : i8_fromNaN; 
         const int8_t NegOverflowResponse = saturate ? i8_minNegativeValue : i8_fromNegOverflow;