#include <string.h>
#include <assert.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

#include <malloc.h>

typedef struct _CVTDescriptor
{
	unsigned char descriptor_tag; 
	unsigned char descriptor_len;
	unsigned char descriptor_data[128]; 
} CVTDescriptor;

void makefile(char * outputName, unsigned char *header, unsigned char *buff, unsigned char nBytes, int count)
{
	FILE * pFile;
	pFile = fopen(outputName , "wb" );
	int i =0;
	for(i=0;i<count;i++)
	{
		fwrite (header , 1 ,3 , pFile );
		fwrite (buff , 1 ,nBytes , pFile );	
	}

	fclose (pFile);

}


int main(int argc, char *argv[])
{
	//code_version_table	
	unsigned char code_version_table_tag[3] = {0x9F, 0x9C, 0x02}; // 0x9F9C02 fixed
	unsigned char length_field = 0;
	unsigned char number_of_descriptors = 3; // 0: vendor ID, 1: hardware version, 2:software version
	CVTDescriptor descriptors[3];
	unsigned char download_type = 0; // 0: one-way, 1: always on demand, 2: DOCSIS tftp, 3: Download unsupported, 4: conditional on demand
	unsigned char download_command = 0; // 0: download now, 1: deferred download, 2: no exception
	unsigned short frequency_vector = 0; // frequecny of the download carousel
	unsigned char transport_value = 0; // 0: DOCSIS channel, 1: FAT channelQAM64, 2: FAT channel/QAM256
	unsigned short PID = 0; //low 13 bits
	unsigned char code_file_name_length = 0;
	unsigned char code_file_name_byte[128] = {0,};
	unsigned char code_verification_certificate = 0xFF;

	unsigned char *pCvt = 0;
	unsigned char pCvtHeader[3] = {0xD9, 0x30, 0x00};
	unsigned long swMajorversion = 0;
	unsigned long swMinorversion = 0;

	char filename[20] = {0,};
	int i =0;
	
	memset(descriptors, 0 ,sizeof(descriptors));
	//vendor id
	descriptors[0].descriptor_tag = 0x00;
	descriptors[0].descriptor_len = 3;
	memcpy(descriptors[0].descriptor_data,argv[1],descriptors[0].descriptor_len);

	//hardware version
	descriptors[1].descriptor_tag = 0x01;
	descriptors[1].descriptor_len = 4;
	memcpy(descriptors[1].descriptor_data,argv[2],descriptors[1].descriptor_len);

	//software version
	swMajorversion = atoi(argv[3]);
	swMinorversion = atoi(argv[4]);
	descriptors[2].descriptor_tag = 0x02;
	descriptors[2].descriptor_len = 4;
	descriptors[2].descriptor_data[0] = (swMajorversion/0x100)%256;
	descriptors[2].descriptor_data[1] = (swMajorversion)%256;
	descriptors[2].descriptor_data[2] = (swMinorversion/0x100)%256;
	descriptors[2].descriptor_data[3] = (swMinorversion)%256;

	download_type = 0x00;
	download_command = atoi(argv[5]);
	
	frequency_vector = 4*atoi(argv[6]); 
	transport_value = atoi(argv[7]);

	
	PID = atoi(argv[8])&0x1FFF;

	code_file_name_length = atoi(argv[9]);
	memcpy(code_file_name_byte, argv[10], code_file_name_length);

	length_field = 3 /*code_version_table_tag*/
		+ 1 /*length_field*/
		+ 1 /*number_of_descriptors*/
		+ 1 /*descriptors[0].descriptor_tag*/
		+ 1 /*descriptors[0].descriptor_len*/
		+ descriptors[0].descriptor_len/*descriptors[0].descriptor_data*/
		+ 1 /*descriptors[1].descriptor_tag*/
		+ 1 /*descriptors[1].descriptor_len*/
		+ descriptors[1].descriptor_len/*descriptors[1].descriptor_data*/
		+ 1 /*descriptors[2].descriptor_tag*/
		+ 1 /*descriptors[2].descriptor_len*/
		+ descriptors[2].descriptor_len/*descriptors[2].descriptor_data*/
		+ 1 /*download_type 4bits + download_command 4bits*/
		+ 2 /*frequency_vector*/
		+ 1 /*transport_value*/
		+ 2 /*reserved 3bits + PID 13bits*/
		+ 1 /*code_file_name_length*/
		+ code_file_name_length /*code_file_name_byte*/
		+ 1; /*code_verification_certificate*/

	pCvt = (unsigned char *)malloc(length_field);
	memset(pCvt, 0 , length_field);

	pCvt[0] = code_version_table_tag[0];
	pCvt[1] = code_version_table_tag[1];
	pCvt[2] = code_version_table_tag[2];
	pCvt[3] = length_field;
	pCvt[4] = number_of_descriptors;
	pCvt[5] = descriptors[0].descriptor_tag;
	pCvt[6] = descriptors[0].descriptor_len;
	pCvt[7] = descriptors[0].descriptor_data[0];
	pCvt[8] = descriptors[0].descriptor_data[1];
	pCvt[9] = descriptors[0].descriptor_data[2];
	pCvt[10] = descriptors[1].descriptor_tag;
	pCvt[11] = descriptors[1].descriptor_len;
	pCvt[12] = descriptors[1].descriptor_data[0];
	pCvt[13] = descriptors[1].descriptor_data[1];
	pCvt[14] = descriptors[1].descriptor_data[2];
	pCvt[15] = descriptors[1].descriptor_data[3];
	pCvt[16] = descriptors[2].descriptor_tag;
	pCvt[17] = descriptors[2].descriptor_len;
	pCvt[18] = descriptors[2].descriptor_data[0];
	pCvt[19] = descriptors[2].descriptor_data[1];
	pCvt[20] = descriptors[2].descriptor_data[2];
	pCvt[21] = descriptors[2].descriptor_data[3];	
	pCvt[22] = ((download_type&0x0F)<<4) + download_command&0x0F;	
	pCvt[23] = (unsigned char)((frequency_vector&0xFF00)>>8);	
	pCvt[24] = (unsigned char)(frequency_vector&0x00FF);	
	pCvt[25] = transport_value;	
	pCvt[26] = (unsigned char)((PID&0xFF00)>>8);	
	pCvt[27] = (unsigned char)(PID&0x00FF);	
	pCvt[28] = code_file_name_length;	
	for(i=29;i<29+code_file_name_length;i++)
	{
		pCvt[i] = code_file_name_byte[i-29];	
	}
	pCvt[29+code_file_name_length] = code_verification_certificate;	
	
	pCvtHeader[0] = 0xD9;
	pCvtHeader[1] = 0x30;
	pCvtHeader[2] = length_field;

	switch(download_command)
	{
		case 0:sprintf(filename,"cvt_dn_%d.%d", (pCvt[18]<<8)+pCvt[19],(pCvt[20]<<8)+pCvt[21]); break;
		case 1:sprintf(filename,"cvt_df_%d.%d", (pCvt[18]<<8)+pCvt[19],(pCvt[20]<<8)+pCvt[21]); break;
 		case 2:sprintf(filename,"cvt_ne_%d.%d", (pCvt[18]<<8)+pCvt[19],(pCvt[20]<<8)+pCvt[21]); break;
		default: break;
 	}
	makefile(filename,pCvtHeader,pCvt,length_field,3000);

	printf("code_version_table_tag = 0x%6x\n",(pCvt[0]<<16) + (pCvt[1]<<8) + pCvt[2]);
	printf("length_field = 0x%2x\n",pCvt[3]);
	printf("number_of_descriptors = 0x%02x\n",pCvt[4]);
	printf("descriptors[0].descriptor_tag = 0x%02x\n",pCvt[5]);
	printf("descriptors[0].descriptor_len = 0x%02x\n",pCvt[6]);
	printf("descriptors[0].descriptor_data = %c%c%c\n",pCvt[7],pCvt[8],pCvt[9]);
	printf("descriptors[1].descriptor_tag = 0x%02x\n",pCvt[10]);
	printf("descriptors[1].descriptor_len = 0x%02x\n",pCvt[11]);
	printf("descriptors[1].descriptor_data = %c%c%c%c\n",pCvt[12],pCvt[13],pCvt[14],pCvt[15]);
	printf("descriptors[2].descriptor_tag = 0x%02x\n",pCvt[16]);
	printf("descriptors[2].descriptor_len = 0x%02x\n",pCvt[17]);
	printf("descriptors[2].descriptor_data = %02x%02x%02x%02x\n",pCvt[18],pCvt[19],pCvt[20],pCvt[21]);
	printf("download_type = 0x%02x\n",(pCvt[22]&0xF0)>>4);
	printf("download_command = 0x%02x\n",pCvt[22]&0x0F);
	printf("frequency_vector = 0x%04x\n",(pCvt[23]<<8) + pCvt[24]);
	printf("transport_value = 0x%02x\n",pCvt[25]);
	printf("PID = 0x%2x\n",(pCvt[26]<<8) + pCvt[27]);
	printf("code_file_name_length = 0x%02x\n",pCvt[28]);
	printf("code_file_name_byte = ");
	
	for(i=29;i<29+code_file_name_length;i++)
	{
		printf("%c",pCvt[i]);
	}
	
	printf("\n");
	printf("code_verification_certificate = 0x%2x\n",pCvt[29+code_file_name_length]);
	free(pCvt);

	return 0;
}