fpga中使用verilog实现输入64个通道数据转换成一路数据输出，且输出时候给出当前输出的通道标识，通道位宽64bit，每一个通道在64个周期内只有一个数据有效，根据64个vld判断数据的有效性。极限情况下，64个周期内64个通道都有数据，且不是按照通道序号连续的。 请给出实现的verilog程序

以下是一个可能的Verilog实现，其中使用了一个FIFO缓冲区来存储输入数据，使用计数器和状态机来控制输出数据和通道标识的生成。

module channel_mux(
    input clk,
    input rst,
    input [63:0] data_in,
    input [63:0] vld_in,
    output reg [63:0] data_out,
    output reg [5:0] channel_out
);

reg [5:0] channel;
reg [5:0] channel_last;
reg [6:0] counter;
reg [6:0] counter_last;
reg [63:0] data_last;
reg [63:0] data_fifo [63:0];
reg [63:0] vld_fifo [63:0];
reg [5:0] read_addr;
reg [5:0] write_addr;
reg [5:0] fifo_count;

always @(posedge clk) begin
    if (rst) begin
        channel <= 0;
        channel_last <= 0;
        counter <= 0;
        counter_last <= 0;
        data_last <= 0;
        read_addr <= 0;
        write_addr <= 0;
        fifo_count <= 0;
    end else begin
        // write input data to FIFO
        if (vld_in != 0) begin
            data_fifo[write_addr] <= data_in;
            vld_fifo[write_addr] <= vld_in;
            write_addr <= write_addr + 1;
            fifo_count <= fifo_count + 1;
        end
        
        // generate output data and channel
        if (fifo_count > 0) begin
            if (counter_last == 63 || vld_fifo[read_addr][counter_last+1] == 1) begin
                data_last <= data_fifo[read_addr];
                channel_last <= channel;
                read_addr <= read_addr + 1;
                fifo_count <= fifo_count - 1;
                counter_last <= 0;
            end else begin
                data_last <= data_last;
                channel_last <= channel_last;
                counter_last <= counter_last + 1;
            end
        end
        
        // update channel counter and state machine
        if (counter == 63 || vld_in != 0) begin
            channel <= channel + 1;
            counter <= 0;
        end else begin
            counter <= counter + 1;
        end
    end
end

assign data_out = data_last;
assign channel_out = channel_last;

endmodule

在这个实现中，输入数据和有效性信号分别通过data_in和vld_in端口传入模块。每当一个输入数据有效时，它会被写入一个FIFO缓冲区，同时计数器和状态机也会更新。输出数据和通道标识分别通过data_out和channel_out端口输出，每当一个通道的数据有效时，它会从FIFO缓冲区中读取并输出，同时通道标识也会更新。在极限情况下，如果64个周期内所有通道都有数据，那么这个实现也能正确地生成输出。