+static int sball_parsepkt(int id, char *data, int len)
+{
+ int i;
+ unsigned int keystate;
+ char c, *rd, *wr;
+ short *mot;
+
+ /* decode data packet, replacing escaped values with the correct ones */
+ rd = wr = data;
+ while(rd < data + len) {
+ if((c = *rd++) == '^') {
+ switch(*rd++) {
+ case 'Q':
+ *wr++ = 0x11; /* XON */
+ break;
+ case 'S':
+ *wr++ = 0x13; /* XOFF */
+ break;
+ case 'M':
+ *wr++ = 13; /* CR */
+ break;
+ case '^':
+ *wr++ = '^';
+ default:
+ fprintf(stderr, "sball decode: ignoring invalid escape code: %xh\n", (unsigned int)c);
+ }
+ } else {
+ *wr++ = c;
+ }
+ }
+ len = wr - data; /* update the decoded length */
+
+ switch(id) {
+ case 'D':
+ if(len != 14) {
+ fprintf(stderr, "sball: invalid data packet, expected 14 bytes, got: %d\n", len);
+ return -1;
+ }
+
+ mot = (short*)(data + 2); /* skip the period */
+ printf("motion: T %+6d %+6d %+6d R %+6d %+6d %+6d\n", mot[0], mot[1], mot[2], mot[3], mot[4], mot[5]);
+ break;
+
+ case 'K':
+ if(len != 2) {
+ fprintf(stderr, "sball: invalid key packet, expected 2 bytes, got: %d\n", len);
+ return -1;
+ }
+ keystate = (data[1] & 0x30) >> 4;
+ print_keystate(keystate);
+ break;
+
+ case 'E':
+ fprintf(stderr, "sball: error:");
+ for(i=0; i<len; i++) {
+ if(isprint(data[i])) {
+ fprintf(stderr, " %c", data[i]);
+ } else {
+ fprintf(stderr, " %02xh", (unsigned int)data[i]);
+ }
+ }
+ break;
+
+ default:
+ /* DEBUG */
+ fprintf(stderr, "sball: got '%c' packet:", (char)id);
+ for(i=0; i<len; i++) {
+ fprintf(stderr, " %02x", (unsigned int)data[i]);
+ }
+ fputc('\n', stderr);
+ }
+ return 0;
+}
+