不幸的是,这个问题很狭窄,但我不知所措。
我有一个自定义的 mex 文件,它包含两个 uint32 列表,每个列表都经过排序并且不包含公共(public)条目,并返回一个包含两个列表中所有条目的排序列表。代码是:
#include "mex.h"
#include "matrix.h"
#include "string.h"
#define MIN(x, y) (((x) < (y)) ? (x) : (y))
void CalculationRoutine(uint32_T* CombinedList, const mwIndex FirstNumels, uint32_T* FirstList, const mwIndex SecondNumels, uint32_T* SecondList) {
mwIndex OutCounter = 0, FirstCounter = 0, SecondCounter = 0;
unsigned int i;
// Short-circuit if there is no ovelap.
if (*FirstList > *(SecondList+SecondNumels-1)) {
memcpy(CombinedList,SecondList,SecondNumels*sizeof(uint32_T));
memcpy(CombinedList+SecondNumels,FirstList,FirstNumels*sizeof(uint32_T));
return;
} else if (*SecondList > *(FirstList+FirstNumels-1)) {
memcpy(CombinedList,FirstList,FirstNumels*sizeof(uint32_T));
memcpy(CombinedList+FirstNumels,SecondList,SecondNumels*sizeof(uint32_T));
return;
}
// These can be done with no exhaustion checking. Leave one item because we
// are doing post-checking in the second loop.
for (i=MIN(FirstNumels, SecondNumels)-1; i--;) {
if (*(FirstList+FirstCounter) < *(SecondList + SecondCounter)) {
*(CombinedList+OutCounter) = *(FirstList+FirstCounter);
FirstCounter++;
} else {
*(CombinedList+OutCounter) = *(SecondList+SecondCounter);
SecondCounter++;
}
OutCounter++;
}
// These ones need exhaustion checking.
while (1){
if (*(FirstList+FirstCounter) < *(SecondList + SecondCounter)) {
*(CombinedList+OutCounter) = *(FirstList+FirstCounter);
FirstCounter++;
if (FirstCounter == FirstNumels) {
// Just copy the rest of the second list.
memcpy(CombinedList+OutCounter+1,SecondList+SecondCounter,(SecondNumels-SecondCounter+1)*sizeof(uint32_T));
return;
}
} else {
*(CombinedList+OutCounter) = *(SecondList+SecondCounter);
SecondCounter++;
if (SecondCounter == SecondNumels) {
// Just copy the rest of the first list.
memcpy(CombinedList+OutCounter+1,FirstList+FirstCounter,(FirstNumels-FirstCounter+1)*sizeof(uint32_T));
return;
}
}
OutCounter++;
}
}
void mexFunction( int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[] ) {
mxArray *CombinedList = NULL;
uint32_T *FirstList, *SecondList;
mwIndex FirstNumels = mxGetNumberOfElements(prhs[0]), SecondNumels = mxGetNumberOfElements(prhs[1]);
//Input Checking
if (!mxIsUint32(prhs[0])) {
mexErrMsgTxt("FirstList must be matrix of uint32.");
}
if (!mxIsUint32(prhs[1])) {
mexErrMsgTxt("SecondList must be a matrix of uint32.");
}
CombinedList = mxCreateNumericMatrix(FirstNumels+SecondNumels, 1, mxUINT32_CLASS, mxREAL);
if (CombinedList == NULL) {
mexErrMsgTxt("SecondList must be a matrix of uint32.");
}
//Short circuit when we have one or the other inputs empty.
if (mxIsEmpty(prhs[0])){
if (!mxIsEmpty(prhs[1])) {
// Return the SecondList verbatim.
//CopyOneInput(mxGetData(CombinedList),SecondNumels, mxGetData(prhs[1]));
memcpy(mxGetData(CombinedList), mxGetData(prhs[1]),SecondNumels*sizeof(uint32_T));
}
plhs[0] = CombinedList;
return;
} else if (mxIsEmpty(prhs[1])) {
// Return the FirstList verbatim.
//CopyOneInput(mxGetData(CombinedList),FirstNumels, mxGetData(prhs[0]));
memcpy(mxGetData(CombinedList), mxGetData(prhs[0]),FirstNumels*sizeof(uint32_T));
plhs[0] = CombinedList;
return;
}
CalculationRoutine(mxGetData(CombinedList),FirstNumels,
mxGetData(prhs[0]),SecondNumels,mxGetData(prhs[1]));
plhs[0] = CombinedList;
}
当我运行调用 mex 文件的代码时,我收到断言检测到的错误(诸如 Found corrupted block 381 in table 5. (invalid table index). 之类的东西)。断言总是出现,但不一定在同一个地方。
如果我恢复到旧版本的代码,则没有问题。所以有些东西正在破坏内存,但我看不到它。我所做的其中一项更改是使用 memcpy,但看不到任何错误。
再次抱歉,这是一个如此狭隘的问题,但我们将不胜感激。
更新:肯定是 memcpy 导致了断言。如果我恢复为在循环中赋值,断言就会停止。在 mex 文件中使用 memcpy 有限制吗?
最佳答案
我重写了 CalculationRoutine
函数如下:
// merge two sorted lists
void CalculationRoutine(uint32_T* C, const mwIndex nA, uint32_T* A,
const mwIndex nB, uint32_T* B)
{
mwIndex indC = 0, indA = 0, indB = 0;
// Short-circuit if there is no ovelap.
if ( A[0] > B[nB-1] ) {
memcpy(C, B, nB*sizeof(uint32_T)); // copy B
memcpy(C+nB, A, nA*sizeof(uint32_T)); // copy A
return;
} else if ( B[0] > A[nA-1] ) {
memcpy(C, A, nA*sizeof(uint32_T)); // copy A
memcpy(C+nA, B, nB*sizeof(uint32_T)); // copy B
return;
}
// loop until one of the two lists is exhausted
while( indA < nA && indB < nB ) {
if( A[indA] < B[indB] ) {
C[indC++] = A[indA++];
} else {
C[indC++] = B[indB++];
}
}
// process remaining items in the smaller list
//if( indA < nA ) memcpy(C+indC, A+indA, (nA-indA)*sizeof(uint32_T));
//if( indB < nB ) memcpy(C+indC, B+indB, (nB-indB)*sizeof(uint32_T));
while( indA < nA ) C[indC++] = A[indA++];
while( indB < nB ) C[indC++] = B[indB++];
}
下面是我测试其正确性/性能的方式:
numIter = 1000; numX = 250; numY = 1000;
x = sort(randi(intmax('uint32'), [250 numIter],'uint32'));
y = sort(randi(intmax('uint32'), [1000 numIter],'uint32'));
M1 = zeros(size(x,1)+size(y,1),numIter,'uint32');
M2 = zeros(size(x,1)+size(y,1),numIter,'uint32');
tic
for i=1:numIter
M1(:,i) = mySort(x(:,i),y(:,i));
end
toc
tic
for i=1:numIter
M2(:,i) = sort([x(:,i);y(:,i)]);
end
toc
assert( isequal(M1,M2) )
时间是:
Elapsed time is 0.029080 seconds. # mySort
Elapsed time is 0.074132 seconds. # sort
关于c - MexFile 导致 "Assertion detected"错误 - mexfiles 中的 memcpy 有问题吗?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6515564/