将参数从 Python 传递到 C 的问题

Question

我对 Python 做了一个 C 扩展。当我从 python 调用 writeByte(..) 时遇到问题。无论我在 python 中作为参数输入什么数字，当我在 C 函数中打印它时，该值都将为零。

test.py：

import myTest_1024LS
myTest_1024LS.findInterface()
myTest_1024LS.writeByte(0x01, 0x43)

setup.py：

from distutils.core import setup, Extension

module1 = Extension('myTest_1024LS', 
include_dirs = ['/usr/local/include'], 
libraries = ['hid'], 
library_dirs = ['/usr/local/include', '/Home/NetBeansProjects/MCCDAQ/usb1024LS_with_py'],
sources = [ 'pmd.c', 'usb-1024LS.c', 'myTest_1024LS.c'],
language = 'c', )

setup (name = 'myTest_1024LS',
   ext_modules = [module1])

myTest_1024LS.c：

void findInterface(void){
int interface;
hid_return ret;
ret = hid_init();
if (ret != HID_RET_SUCCESS) {
        fprintf(stderr, "hid_init failed with return code %d\n", ret);
        exit(1);
}

if ((interface = PMD_Find_Interface(&hid, 0, USB1024LS_PID)) >= 0) {
        printf("USB 1024LS Device is found! interface = %d\n", interface);
} else if ((interface = PMD_Find_Interface(&hid, 0, USB1024HLS_PID)) >= 0) {
        printf("USB 1024HLS Device is found! interface = %d\n", interface);
} else {
        fprintf(stderr, "USB 1024LS and USB 1024HLS not found.\n");
        exit(1);
}
}

void writeByte(__u8 port, __u8 byte){
printf("%x, %x\n", port, byte);
if((port==DIO_PORTA)||(port==DIO_PORTB)){       
    usbDOut_USB1024LS(hid, port, byte);
    printf("You wrote 0x%x to port %x\n", byte, port);
}else if(port == DIO_PORTC){
    printf("Port C is splitted into PORT C HIGH and LOW,\nthis means that your byte is separated into two nibbles before sending\n");
    __u8 nib_low = byte & 0x0F;
    __u8 nib_high = (byte & 0xF0)>>4;
    usbDOut_USB1024LS(hid, DIO_PORTC_LOW, nib_low);
    usbDOut_USB1024LS(hid, DIO_PORTC_HI, nib_high);
}else{
    printf("Port is not intended for bytes\n");
    exit(1);
}
}

PyDoc_STRVAR(myTest_1024LS__doc__, "myTes_1024LS point evaluation kernel");
PyDoc_STRVAR(findInterface__doc__, "find device");
PyDoc_STRVAR(writeByte__doc__, "write byte");

static PyMethodDef myTest_methods[] = {
{"findInterface", py_findInterface, METH_VARARGS, findInterface__doc__},
{"writeByte", py_writeByte, METH_VARARGS, writeByte__doc__}, 
{NULL, NULL}
};

PyMODINIT_FUNC initmyTest_1024LS(void){
Py_InitModule3("myTest_1024LS", myTest_methods, myTest_1024LS__doc__);

}

static PyObject *py_findInterface(PyObject *self, PyObject *args){

if(!PyArg_ParseTuple(args, "")){
    return NULL;
}
findInterface();
return Py_BuildValue("i",0);
}

static PyObject *py_writeByte(PyObject *self, PyObject *args){
__u8 port=1, byte=4;
if(!PyArg_ParseTuple(args, "dd|i:writeByte", &port, &byte)){
    return NULL;
}
writeByte((__u8)port, (__u8)byte);
return Py_BuildValue("i",0);
}

如您所见，在 writeByte 函数中，我首先打印端口和字节值，以检查值是否正确。到目前为止，当它们真的与零不同时，它们总是为零。 我也尝试将十进制值而不是十六进制值作为参数，但似乎没有帮助。

可能是数据类型的问题，但是我找不到...

在我开始这个 python/c 项目之前，C 代码已经在 C 主函数中进行了测试。

Answer 1

@The Paramagnetic Croissant 在评论中写道：

您错误地使用了PyArg_ParseTuple()。您期待两个强制性的double 参数和一个可选的int 参数。这似乎不是你真正需要的。

OP 写道：

啊，谢谢！我只是用“ii”代替，当然......然后它工作了