使用Vitis HLS实现元胞自动机时遇Top函数未找到错误求助

尝试使用Vitis HLS实现元胞自动机，测试仿真运行正常，但综合时反复出现以下错误：

ERROR: [HLS 214-157] Top function not found: there is no function named 'ca'  cellular_automata:cellular_automata  Mar 29, 2023, 3:14:13 PM

期望生成Vivado IP，但编译因该错误终止，以下是实现代码及解决思路：

ca.hpp:

#include <cstdio>
#include <cinttypes>

#include "ap_axi_sdata.h"
#include "hls_stream.h"

#define N 8

typedef int DataType;

typedef hls::axis<DataType, 0, 0, 0> packet;
typedef hls::stream<packet> stream;

bool is_equal(DataType previous_state[3], DataType test[3]);
DataType rule30(DataType previous_state[3]);

template <typename T> void ca(T input[N], T output[N]);

ca.cpp:

#include "ca.hpp"

DataType rule30_111[3] = {1, 1, 1};
DataType rule30_110[3] = {1, 1, 0};
DataType rule30_101[3] = {1, 0, 1};
DataType rule30_011[3] = {0, 1, 1};
DataType rule30_100[3] = {1, 0, 0};
DataType rule30_010[3] = {0, 1, 0};
DataType rule30_001[3] = {0, 0, 1};
DataType rule30_000[3] = {0, 0, 0};

bool is_equal(DataType previous_state[3], DataType test[3]){
    int check = 1;
    for(int j = 0; j < 3; j++){
        check = previous_state[j]==test[j];
        if(check == 0){
            return 0;
        }
    }
    return 1;
}

DataType rule30(DataType previous_state[3]){
    if(is_equal(previous_state, rule30_111)){
        return 0;
    } else if(is_equal(previous_state, rule30_110)){
        return 0;
    } else if(is_equal(previous_state, rule30_101)){
        return 0;
    } else if(is_equal(previous_state, rule30_011)){
        return 1;
    } else if(is_equal(previous_state, rule30_001)){
        return 1;
    } else if(is_equal(previous_state, rule30_010)){
        return 1;
    } else if(is_equal(previous_state, rule30_100)){
        return 1;
    } else if(is_equal(previous_state, rule30_000)){
        return 0;
    } else {
        return -1;
    }
}

template <typename T> void ca(T input[N], T output[N]) {
    for(int i = 0; i < N; i++){
        if(i > 0 and i < N - 1){
            T previous_state[3] = {input[i - 1], input[i], input[i + 1]};
            output[i] = rule30(previous_state);
        }
    }
}

void cellular_autmata(stream &signal, stream &result) {
#pragma HLS INTERFACE axis port=signal
#pragma HLS INTERFACE axis port=result
#pragma HLS INTERFACE ap_ctrl_none port=return

    DataType in[N];
    DataType out[N];

read:
    for(int i = 0; i < N; i++){
        packet temp = signal.read();
        in[i] = temp.data;
    }

    ca<DataType>(in, out);

write:
    for(int i = 0; i < N; i++){
        packet temp;
        temp.data = out[i];
        ap_uint<1> last = 0;
        if(i == N - 1){
            last = 1;
        }
        temp.last = last;
        temp.keep = -1;
        result.write(temp);
    }
}

ca_tb.cpp:

#include "ca.hpp"

void sw_ca(DataType input[], DataType output[]) {
    for(int i = 0; i < N; i++){
        if(i > 0 and i < N - 1){
            DataType rule[3] = {input[i - 1], input[i], input[i + 1]};
            output[i] = rule30(rule);
        }
    }
}

int main(void) {
    /*initialise*/
    int i, err;

    DataType in[N] = {0,0,1,1,0,0,1,1};
    DataType out_sw[N];
    DataType out_hw[N];

    std::cout << "signal in:" << std::endl;
    for (i = 0; i < N; i++) {
        //in[i] = i % 2;
        out_sw[i] = 0;
        out_hw[i] = 0;
        std::cout << in[i] << " ";
    }
    std::cout << std::endl;

    std::cout << std::endl;

    /* software */
    sw_ca(in, out_sw);
    std::cout<<"software kernel complete
"<<std::endl;

    /* hardware */
    ca<DataType>(in, out_hw);
    std::cout<<"hardware kernel complete
"<<std::endl;

    /* comparison */
    err = 1;
    std::cout << "signal out:" << std::endl;
    for(i = 0; i < N; i++){
        if(out_sw[i] != out_hw[i]){
            err = 0;
        }
        std::cout << out_hw[i] << " ";
    }
    std::cout<<std::endl;

    if (err == 1) {
        printf("Test successful!
");
        return 0;
    }
    printf("Test failed
");
    return 1;
}

错误原因及解决步骤 #

核心问题 #

Vitis HLS无法将模板函数作为顶层函数进行综合，你当前指定的顶层函数是ca（模板函数），这不符合HLS的综合规则；另外代码中实际的硬件入口是带有AXI接口约束的cellular_autmata函数（注意存在拼写错误），这个才是正确的顶层候选。

具体解决步骤 #

1. 修正顶层函数配置：在Vitis HLS项目的综合设置中，将顶层函数从ca改为cellular_autmata（建议先修正函数名为cellular_automata，避免后续拼写相关问题）。
2. 确认模板函数实例化：ca模板函数被cellular_autmata以DataType类型实例化调用，HLS会自动处理该实例化后的子模块，无需额外配置。
3. 修复函数名拼写错误：cellular_autmata中的autmata是拼写错误，应改为automata，否则可能导致IP生成或后续调用时出现识别问题。
4. 完善输出边界处理：当前ca函数中未处理首尾元素（i=0和i=N-1）的输出值，建议根据元胞自动机规则补充边界逻辑（比如采用循环边界、固定边界值等），避免输出数组存在未初始化的不确定值。

内容的提问来源于stack exchange，提问作者AKRA