Copyright (c) 2017, Microsoft Corporation\r
\r
All rights reserved.\r
- Redistribution and use in source and binary forms, with or without\r
- modification, are permitted provided that the following conditions are met:\r
- 1. Redistributions of source code must retain the above copyright notice,\r
- this list of conditions and the following disclaimer.\r
- 2. Redistributions in binary form must reproduce the above copyright notice,\r
- this list of conditions and the following disclaimer in the documentation\r
- and/or other materials provided with the distribution.\r
-\r
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND\r
- ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\r
- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.\r
- IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,\r
- INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,\r
- BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,\r
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF\r
- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE\r
- OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF\r
- ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.\r
+ SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include <Base.h>\r
#include <Library/SafeIntLib.h>\r
+#include <Library/BaseLib.h>\r
\r
\r
//\r
// Magnitude of MIN_INT64 as expressed by a UINT64 number.\r
//\r
-#define MIN_INT64_MAGNITUDE ((((UINT64) - (MIN_INT64 + 1))) + 1)\r
+#define MIN_INT64_MAGNITUDE (((UINT64)(- (MIN_INT64 + 1))) + 1)\r
\r
//\r
// Conversion functions\r
// b * c must be less than 2^32 or there would be bits in the high 64-bits\r
// then there must be no overflow of the resulting values summed up.\r
//\r
- DwordA = (UINT32)(Multiplicand >> 32);\r
- DwordC = (UINT32)(Multiplier >> 32);\r
+ DwordA = (UINT32)RShiftU64 (Multiplicand, 32);\r
+ DwordC = (UINT32)RShiftU64 (Multiplier, 32);\r
\r
//\r
// common case -- if high dwords are both zero, no chance for overflow\r
// now sum them all up checking for overflow.\r
// shifting is safe because we already checked for overflow above\r
//\r
- if (!RETURN_ERROR (SafeUint64Add (ProductBC << 32, ProductAD << 32, &UnsignedResult))) {\r
+ if (!RETURN_ERROR (SafeUint64Add (LShiftU64 (ProductBC, 32), LShiftU64 (ProductAD, 32), &UnsignedResult))) {\r
//\r
// b * d\r
//\r
)\r
{\r
RETURN_STATUS Status;\r
- INT64 SignedResult;\r
\r
if (Result == NULL) {\r
return RETURN_INVALID_PARAMETER;\r
}\r
\r
- SignedResult = Augend + Addend;\r
-\r
//\r
- // Adding positive to negative never overflows.\r
- // If you add two positive numbers, you expect a positive result.\r
- // If you add two negative numbers, you expect a negative result.\r
- // Overflow if inputs are the same sign and output is not that sign.\r
+ // * An Addend of zero can never cause underflow or overflow.\r
+ //\r
+ // * A positive Addend can only cause overflow. The overflow condition is\r
+ //\r
+ // (Augend + Addend) > MAX_INT64\r
+ //\r
+ // Subtracting Addend from both sides yields\r
+ //\r
+ // Augend > (MAX_INT64 - Addend)\r
+ //\r
+ // This condition can be coded directly in C because the RHS will neither\r
+ // underflow nor overflow. That is due to the starting condition:\r
+ //\r
+ // 0 < Addend <= MAX_INT64\r
+ //\r
+ // Multiplying all three sides by (-1) yields\r
+ //\r
+ // 0 > (-Addend) >= (-MAX_INT64)\r
+ //\r
+ // Adding MAX_INT64 to all three sides yields\r
+ //\r
+ // MAX_INT64 > (MAX_INT64 - Addend) >= 0\r
+ //\r
+ // * A negative Addend can only cause underflow. The underflow condition is\r
+ //\r
+ // (Augend + Addend) < MIN_INT64\r
+ //\r
+ // Subtracting Addend from both sides yields\r
+ //\r
+ // Augend < (MIN_INT64 - Addend)\r
+ //\r
+ // This condition can be coded directly in C because the RHS will neither\r
+ // underflow nor overflow. That is due to the starting condition:\r
+ //\r
+ // MIN_INT64 <= Addend < 0\r
+ //\r
+ // Multiplying all three sides by (-1) yields\r
+ //\r
+ // (-MIN_INT64) >= (-Addend) > 0\r
+ //\r
+ // Adding MIN_INT64 to all three sides yields\r
+ //\r
+ // 0 >= (MIN_INT64 - Addend) > MIN_INT64\r
//\r
- if (((Augend < 0) == (Addend < 0)) &&\r
- ((Augend < 0) != (SignedResult < 0))) {\r
+ if (((Addend > 0) && (Augend > (MAX_INT64 - Addend))) ||\r
+ ((Addend < 0) && (Augend < (MIN_INT64 - Addend)))) {\r
*Result = INT64_ERROR;\r
Status = RETURN_BUFFER_TOO_SMALL;\r
} else {\r
- *Result = SignedResult;\r
+ *Result = Augend + Addend;\r
Status = RETURN_SUCCESS;\r
}\r
\r
OUT INT32 *Result\r
)\r
{\r
- return SafeInt64ToInt32 (((INT64)Multiplicand) *((INT64)Multiplier), Result);\r
+ return SafeInt64ToInt32 (MultS64x64 (Multiplicand, Multiplier), Result);\r
}\r
\r
/**\r
if (UnsignedResult > MIN_INT64_MAGNITUDE) {\r
*Result = INT64_ERROR;\r
Status = RETURN_BUFFER_TOO_SMALL;\r
+ } else if (UnsignedResult == MIN_INT64_MAGNITUDE) {\r
+ *Result = MIN_INT64;\r
} else {\r
*Result = - ((INT64)UnsignedResult);\r
}\r
projects / mirror_edk2.git / blobdiff