---
title: Istft
description: "安全声明："
url: https://www.hiascend.com/document/detail/zh/canncommercial/latest/API/SiP/SIP_API_0085.html
sourcePath: /source/zh/canncommercial/900/API/SiP/SIP_API_0085.html
indexId: 229dcd73edf12025dee69f84398b2d71b3f078cde6aaa49037bbcea2c945ca2255
---
# Istft

安全声明：

该样例旨在提供快速上手、开发和调试算子的最小化实现，其核心目标是使用最精简的代码展示算子的核心功能，而非提供生产级的安全保障。

不推荐用户直接将示例代码作为业务代码，若用户将示例代码应用在自身的真实业务场景中且发生了安全问题，则需用户自行承担。

#### Istft

Istft算子的调用示例：
```
#include <iostream>
#include <vector>
#include "asdsip.h"
#include "acl/acl.h"
#include "aclnn/acl_meta.h"
using namespace AsdSip;
#define CHECK_RET(cond, return_expr) \
do {                             \
if (!(cond)) {               \
return_expr;             \
}                            \
} while (0)
#define LOG_PRINT(message, ...)         \
do {                                \
printf(message, ##__VA_ARGS__); \
} while (0)
#define ASD_STATUS_CHECK(err)                                                \
do {                                                                     \
AsdSip::AspbStatus err_ = (err);                                     \
if (err_ != AsdSip::ErrorType::ACL_SUCCESS) {                                      \
std::cout << "Execute failed." << std::endl; \
exit(-1);                                                        \
}                                                                    \
} while (0)
int64_t GetShapeSize(const std::vector<int64_t> &shape)
{
int64_t shapeSize = 1;
for (auto i : shape) {
shapeSize *= i;
}
return shapeSize;
}
int Init(int32_t deviceId, aclrtStream *stream)
{
// 固定写法，AscendCL初始化
auto ret = aclInit(nullptr);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclInit failed. ERROR: %d\n", ret); return ret);
ret = aclrtSetDevice(deviceId);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclrtSetDevice failed. ERROR: %d\n", ret); return ret);
ret = aclrtCreateStream(stream);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclrtCreateStream failed. ERROR: %d\n", ret); return ret);
return 0;
}
template <typename T>
int CreateAclTensor(const std::vector<T> &hostData, const std::vector<int64_t> &shape, void **deviceAddr,
aclDataType dataType, aclTensor **tensor)
{
auto size = GetShapeSize(shape) * sizeof(T);
// 调用aclrtMalloc申请device侧内存
auto ret = aclrtMalloc(deviceAddr, size, ACL_MEM_MALLOC_HUGE_FIRST);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclrtMalloc failed. ERROR: %d\n", ret); return ret);
// 调用aclrtMemcpy将host侧数据复制到device侧内存上
ret = aclrtMemcpy(*deviceAddr, size, hostData.data(), size, ACL_MEMCPY_HOST_TO_DEVICE);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclrtMemcpy failed. ERROR: %d\n", ret); return ret);
// 计算连续tensor的strides
std::vector<int64_t> strides(shape.size(), 1);
for (int64_t i = shape.size() - 2; i >= 0; i--) {
strides[i] = shape[i + 1] * strides[i + 1];
}
// 调用aclCreateTensor接口创建aclTensor
*tensor = aclCreateTensor(shape.data(),
shape.size(),
dataType,
strides.data(),
0,
aclFormat::ACL_FORMAT_ND,
shape.data(),
shape.size(),
*deviceAddr);
return 0;
}
int main()
{
int32_t deviceId = 0;
aclrtStream stream;
auto ret = Init(deviceId, &stream);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("Init acl failed. ERROR: %d\n", ret); return ret);
// 创造tensor的Host侧数据
int64_t channel = 10, nFrames = 20, nFft = 16, hopLen = 4, winLen = 16;
int64_t outLen = nFft + hopLen * (nFrames - 1) - nFft / 2 - nFft / 2;
bool returnComplex = true;
bool center = true, normalized = false, onesidedOpt = false;
const int64_t tensorInSize = channel * nFrames * nFft;
const int64_t tensorWinSize = winLen;
const int64_t tensorOutSize = channel * outLen;
std::vector<int64_t> selfShape = {channel, nFft, nFrames};
std::vector<int64_t> winShape = {winLen};
std::vector<int64_t> outShape = {channel, outLen};
std::vector<std::complex<float>> inputHostData(tensorInSize, std::complex<float>(0, 0));
for (int i = 0; i < tensorInSize; i++) {
inputHostData[i] = std::complex<float>(i *  200.0f / tensorInSize - 100, i *  100.0f / tensorInSize - 50);
}
std::vector<float> winHostData(tensorWinSize, 0.0f);
for (int i = 0; i < tensorWinSize; i++) {
winHostData[i] = 1.0f / winLen * i ;
}
std::vector<std::complex<float>> outHostData(tensorOutSize, std::complex<float>(0, 0));
void *inputDeviceAddr = nullptr;
void *winDeviceAddr = nullptr;
void *outDeviceAddr = nullptr;
aclTensor *input = nullptr;
aclTensor *win = nullptr;
aclTensor *out = nullptr;
ret = CreateAclTensor(inputHostData, selfShape, &inputDeviceAddr, aclDataType::ACL_COMPLEX64, &input);
CHECK_RET(ret == ::ACL_SUCCESS, return ret);
ret = CreateAclTensor(winHostData, winShape, &winDeviceAddr, aclDataType::ACL_FLOAT, &win);
CHECK_RET(ret == ::ACL_SUCCESS, return ret);
ret = CreateAclTensor(outHostData, outShape, &outDeviceAddr, aclDataType::ACL_COMPLEX64, &out);
CHECK_RET(ret == ::ACL_SUCCESS, return ret);
asdFftHandle handle;
asdFftCreate(handle);
asdFftIstftMakePlan(handle, input, nFft, hopLen, winLen, center, normalized, onesidedOpt, 0, returnComplex);
size_t work_size;
asdFftGetWorkspaceSize(handle, work_size);
void *workspaceAddr = nullptr;
if (work_size > 0) {
ret = aclrtMalloc(&workspaceAddr, static_cast<int64_t>(work_size), ACL_MEM_MALLOC_HUGE_FIRST);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("allocate workspace failed. ERROR: %d\n", ret); return ret);
}
asdFftSetWorkspace(handle, (uint8_t *)workspaceAddr);
asdFftSetStream(handle, stream);
ASD_STATUS_CHECK(asdFftExecIstft(handle, input, win, out));
ret = aclrtSynchronizeStream(stream);
CHECK_RET(ret == ::ACL_SUCCESS, LOG_PRINT("aclrtSynchronizeStream failed. ERROR: %d\n", ret); return ret);
asdFftDestroy(handle);
auto size = GetShapeSize(outShape);
std::vector<std::complex<float>> outData(size, 0);
ret = aclrtMemcpy(outData.data(),
outData.size() * sizeof(outData[0]),
outDeviceAddr,
size * sizeof(outData[0]),
ACL_MEMCPY_DEVICE_TO_HOST);
// 打印输出tensor值中前16个
for (int64_t i = 0; i < 16; i++) {
std::cout << static_cast<std::complex<float>>(outData[i]) << "\t";
}
std::cout << "\nend result" << std::endl;
std::cout << "Execute successfully." << std::endl;
aclDestroyTensor(input);
aclDestroyTensor(win);
aclDestroyTensor(out);
aclrtFree(inputDeviceAddr);
aclrtFree(winDeviceAddr);
aclrtFree(outDeviceAddr);
if (work_size > 0) {
aclrtFree(workspaceAddr);
}
aclrtDestroyStream(stream);
aclrtResetDevice(deviceId);
aclFinalize();
return 0;
}
```