380 lines
8.6 KiB
C
380 lines
8.6 KiB
C
#include "frame.h"
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#include <stdio.h>
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extern int window_length;
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extern int raw_data_length;
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extern int frame_number_range;
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/* 33 crc*/
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short crc[] = {1, 0, 0, 0, 0, 0,
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1, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 1,
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0, 0, 0, 1, 1, 1,
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0, 1, 1, 0, 1, 1,
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0, 1, 1, 1};
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short send_receive_num[][3] = {{0, 0, 0},
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{0, 0, 1},
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{0, 1, 0},
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{0, 1, 1},
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{1, 0, 0},
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{1, 0, 1},
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{1, 1, 0},
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{1, 1, 1}
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};
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static Frame *fill_flag_and_fcs(Frame *p_frame) {
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short s[] = {0, 1, 1, 1, 1, 1, 1, 0};
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int i;
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for (i = 0; i < 8; ++i) {
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p_frame ->head_flag[i] = s[i];
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p_frame ->rail_flag[i] = s[i];
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}
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for (i = 0; i < (sizeof(crc) / sizeof(short) - 1); ++i) {
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p_frame ->fcs[i] = 0;
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}
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return p_frame;
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}
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static Frame *create_generic_unnumbered_frame(Frame *p_frame) {
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fill_flag_and_fcs(p_frame);
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p_frame ->control[0] = 1;
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p_frame ->control[1] = 1;
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p_frame ->s.size = 0;
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return p_frame;
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}
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static Frame *create_generic_info_frame(Frame *p_frame) {
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fill_flag_and_fcs(p_frame);
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p_frame ->control[0] = 0;
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p_frame ->s.size = 0;
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return p_frame;
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}
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static Frame *create_generic_sup_frame(Frame *p_frame) {
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fill_flag_and_fcs(p_frame);
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p_frame ->control[0] = 1;
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p_frame ->control[1] = 0;
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p_frame ->s.size = 0;
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return p_frame;
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}
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static void convert_frame_to_seq(Frame *p_frame, short seq[], int *size) {
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int i;
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(*size) = 0;
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for (i = 0; i < 8; ++i) {
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seq[*size] = p_frame ->address[i];
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++(*size);
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}
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for (i = 0; i < 8; ++i) {
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seq[*size] = p_frame ->control[i];
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++(*size);
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}
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for (i = 0; i < p_frame ->s.size; ++i) {
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if (1 == (p_frame ->s.infor_type[i])) {
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seq[*size] = p_frame ->s.information[i];
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++(*size);
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}
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}
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for (i = 0; i < sizeof(crc) / sizeof(short) - 1; ++i) {
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seq[*size] = p_frame ->fcs[i];
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++(*size);
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}
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}
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/* 0 has been filled before calling this method.*/
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static int seq_fcs(short seq[], int size) {
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int i;
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int non_zero = 0;
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int temp_non_zero;
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bool new_non_zero = 0;
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for (i = 0; i < size; ++i) {
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if (1 == seq[i]) {
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non_zero = i;
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new_non_zero = 1;
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break;
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}
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}
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for (;non_zero <= size - sizeof(crc)/sizeof(short);) {
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new_non_zero = 0;
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temp_non_zero = -1;
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for (i = non_zero; i < non_zero + sizeof(crc)/sizeof(short); ++i) {
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seq[i] ^= crc[i - non_zero];
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if ((1 == seq[i]) && !new_non_zero) {
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temp_non_zero = i;
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new_non_zero = 1;
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}
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}
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if (-1 == temp_non_zero) {
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for (i = non_zero + sizeof(crc) / sizeof(short); i < size; ++i) {
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if (1 == seq[i]) {
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non_zero = i;
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break;
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}
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}
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if (i == size) return -1;
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} else {
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non_zero = temp_non_zero;
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}
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}
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return non_zero;
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}
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/*Here add fcs to one frame*/
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static void add_fcs_to_frame(Frame *p_frame) {
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short seq[1024];
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int size = 0;
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int i;
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int non_zero = 0;
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convert_frame_to_seq(p_frame, seq, &size);
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seq_fcs(seq, size);
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for (i = 0; i < sizeof(crc)/sizeof(short) - 1; ++i) {
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p_frame ->fcs[i] = seq[size - (sizeof(crc)/sizeof(short) - 1) + i];
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}
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}
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static void convert_decimal_2_binary(int decimal, short binary[]) {
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binary[2] = decimal % 2;
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binary[0] = decimal / 4;
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binary[1] = (decimal - binary[0] * 4) / 2;
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}
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/*Here create SABME, UA and DISC.*/
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Frame create_unnumbered_frame(short addr[], enum FRAME_TYPE ft, bool p_f) {
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Frame f;
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short s1[] = {1, 1, 0, 1, 1, 0};/* For SABME*/
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short s2[] = {0, 0, 0, 1, 1, 0};/* For UA*/
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short s3[] = {0, 0, 0, 0, 1, 0};/* For DISC*/
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int i;
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create_generic_unnumbered_frame(&f);
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for (i = 0; i < 8; ++i) {
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f.address[i] = addr[i];
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}
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switch(ft) {
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case SABME :
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for (i = 2; i < 8; ++i) {
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f.control[i] = s1[i - 2];
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}
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break;
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case UA :
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for (i = 2; i < 8; ++i) {
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f.control[i] = s2[i - 2];
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}
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break;
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case DISC :
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for (i = 2; i < 8; ++i) {
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f.control[i] = s3[i - 2];
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}
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break;
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default : fprintf(stderr, "Call create unnumbered frame error!\n");
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break;
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}
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f.control[4] = p_f;
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add_fcs_to_frame(&f);
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return f;
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}
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Frame create_sup_frame(short addr[], enum FRAME_TYPE ft, bool p_f, short want_receive) {
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Frame f;
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int i;
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short next_receive[3];
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create_generic_sup_frame(&f);
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for (i = 0; i < 8; ++i) {
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f.address[i] = addr[i];
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}
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f.control[2] = 0;
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switch(ft) {
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case RR :
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f.control[3] = 0;
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break;
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case REJ :
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f.control[3] = 1;
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break;
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default :
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fprintf(stderr, "create sup frame error!\n");
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break;
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}
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f.control[4] = p_f;
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convert_decimal_2_binary(want_receive, next_receive);
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for (i = 5; i < 8; ++i) {
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f.control[i] = next_receive[i - 5];
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}
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add_fcs_to_frame(&f);
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return f;
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}
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/* prequestic : ($end - $start) % $raw_data_length = 0*/
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Frame* create_infor_frames(short addr[], short send_n, bool p_f, short receive_n,
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short data[], int start, int end, Frame *frames) { /*Normal data transferring.*/
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Frame f;
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int i;
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int j;
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int k;
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int ite = 0;
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short receive_number[3];
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short send_number[3];
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if ((end -start + 1) > (850 * window_length)) {
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fprintf(stderr, "One frame takes too long data!\n");
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return &f;
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}
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convert_decimal_2_binary(receive_n, receive_number);
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for (ite = 0; ite < ((end - start) / raw_data_length); ++ite) {
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create_generic_info_frame(&f);
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convert_decimal_2_binary(send_n, send_number);
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for (i = 1; i < 4; ++i) {
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f.control[i] = send_number[i - 1];
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f.control[i + 4] = receive_number[i - 1];
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}
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send_n = (send_n + 1) % frame_number_range;
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f.control[4] = p_f;
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j = 0;
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k = 0;
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/*bit stuffing!*/
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for (i = start + ite * raw_data_length; i < start + (ite + 1) * raw_data_length; ++i) {
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f.s.information[k] = data[i]; f.s.infor_type[k] = 1; ++k; ++f.s.size;
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if (1 == data[i]) {
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if (4 == (i - j)) {
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f.s.information[k] = 0; f.s.infor_type[k] = 0; ++k; ++f.s.size;
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j = i + 1;
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}
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} else {
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j = i + 1;
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}
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}
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add_fcs_to_frame(&f);
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frames[ite] = f;
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}
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return frames;
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}
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short unnumbered[][8] = {
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{1, 1, 1, 1, 0, 1, 1, 0}, /*SABME*/
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{1, 1, 0, 0, 0, 1, 1, 0}, /*UA*/
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{1, 1, 0, 0, 0, 0, 1, 0} /*DISC*/ };
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enum FRAME_TYPE get_frame_type(Frame *p_frame) {
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if (0 == p_frame ->control[0]) {
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return INFOR;
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}
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if (0 == p_frame ->control[1]) {
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if (0 == p_frame ->control[3]) return RR;
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else return REJ;
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} else {
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if (1 == p_frame ->control[2]) return SABME;
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else {
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if (1 == p_frame ->control[5]) return UA;
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else return DISC;
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}
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}
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fprintf(stdout, "Inteprete Frame type error!\n");
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return INFOR;
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}
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void get_address(Frame *p_frame, short *storage) {
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int i;
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for (i = 0; i < 8; ++i) {
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storage[i] = p_frame ->address[i];
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}
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}
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/* Only for INFOR, */
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short get_send_number(Frame *p_frame) {
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int num;
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num = p_frame ->control[1] * 4 + p_frame ->control[2] * 2 + p_frame ->control[3];
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return num;
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}
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/* For INFOR, RR, REJ.*/
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short get_expect_number(Frame *p_frame) {
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int num;
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num = p_frame ->control[5] * 4 + p_frame ->control[6] * 2 + p_frame ->control[7];
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return num;
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}
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/* Only for INFOR.*/
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void get_infor(Frame *p_frame, short *storage, int *size) {
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int i;
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*size = 0;
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for (i = 0; i < p_frame ->s.size; ++i) {
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if (1 == p_frame ->s.infor_type[i]) {
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storage[*size] = p_frame ->s.information[i];
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++(*size);
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}
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}
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}
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/*Here using fcs to judge whether the data is right.*/
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bool is_fcs_right(Frame *p_frame) {
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short seq[1024];
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int size = 0;
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int non_zero;
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int i;
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convert_frame_to_seq(p_frame, seq, &size);
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non_zero = seq_fcs(seq, size);
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if (-1 == non_zero) {
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return 1;
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}
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return 0;
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} |