17  * how to encode a sample stream to 64-bit blocks that will be encryped
19  * first of all, data is collected until a block of 9 samples are received.
20  * of course, a packet may have much more than 9 sample, but is may have
21  * not excacly the multiple of 9 samples. if there is a rest, the next
24  * the block is then converted to 9 uLAW samples without the least sigificant
25  * bit. the result is a 7-bit encoded sample.
39  * the missing bit 0 of the last byte is filled with some
44  * the result will be converted into 9 bytes. the bit 7 is used for
45  * checksumme (CS) for sync (0, 1) and for the last bit:
53  * CS   4(4) 4(3) 4(2) 4(1) 4(0) 5(7) 5(6)
54  * CS   5(5) 5(4) 5(3) 5(2) 5(1) 5(0) 6(7)
55  * CS   6(6) 6(5) 6(4) 6(3) 6(2) 6(1) 6(0)
58  * the checksum is used to detect transmission errors and frame drops.
60  * synchronisation of received block is done by shifting the upper bit of each
62  * (10000), this is used to find the sync. only if sync has been found, the
64  * sum is calculated. if it is incorrect the block is dropped.
67  * if the last block is corrupt, the current decoded block is repeated
73  * crypto-api for faster implementation
344  * Round loop unrolling macros, S is a pointer to a S-Box array
361  * every block with 9 samples is encrypted
366 	int i = 0, j = dsp->bf_crypt_pos;  in dsp_bf_encrypt()
367 	u8 *bf_data_in = dsp->bf_data_in;  in dsp_bf_encrypt()
368 	u8 *bf_crypt_out = dsp->bf_crypt_out;  in dsp_bf_encrypt()
369 	u32 *P = dsp->bf_p;  in dsp_bf_encrypt()
370 	u32 *S = dsp->bf_s;  in dsp_bf_encrypt()
372 	u32 cs;  in dsp_bf_encrypt()  local
420 		/* calculate 3-bit checksumme */  in dsp_bf_encrypt()
421 		cs = yl ^ (yl >> 3) ^ (yl >> 6) ^ (yl >> 9) ^ (yl >> 12) ^ (yl >> 15)  in dsp_bf_encrypt()
436 		bf_crypt_out[5] = ((yr >> 22) & 0x7f) | ((cs << 5) & 0x80);  in dsp_bf_encrypt()
437 		bf_crypt_out[6] = ((yr >> 15) & 0x7f) | ((cs << 6) & 0x80);  in dsp_bf_encrypt()
438 		bf_crypt_out[7] = ((yr >> 8) & 0x7f) | (cs << 7);  in dsp_bf_encrypt()
443 	dsp->bf_crypt_pos = j;  in dsp_bf_encrypt()
450  * every block with 9 bytes is decrypted
456 	u8 j = dsp->bf_decrypt_in_pos;  in dsp_bf_decrypt()
457 	u8 k = dsp->bf_decrypt_out_pos;  in dsp_bf_decrypt()
458 	u8 *bf_crypt_inring = dsp->bf_crypt_inring;  in dsp_bf_decrypt()
459 	u8 *bf_data_out = dsp->bf_data_out;  in dsp_bf_decrypt()
460 	u16 sync = dsp->bf_sync;  in dsp_bf_decrypt()
461 	u32 *P = dsp->bf_p;  in dsp_bf_decrypt()
462 	u32 *S = dsp->bf_s;  in dsp_bf_decrypt()
465 	u8 cs, cs0, cs1, cs2;  in dsp_bf_decrypt()  local
481 		j -= 9;  in dsp_bf_decrypt()
498 		/* calculate 3-bit checksumme */  in dsp_bf_decrypt()
499 		cs = yl ^ (yl >> 3) ^ (yl >> 6) ^ (yl >> 9) ^ (yl >> 12) ^ (yl >> 15)  in dsp_bf_decrypt()
505 		/* check if frame is valid */  in dsp_bf_decrypt()
506 		if ((cs & 0x7) != (((cs2 >> 5) & 4) | ((cs1 >> 6) & 2) | (cs0 >> 7))) {  in dsp_bf_decrypt()
510 				       "checksumme is not correct\n");  in dsp_bf_decrypt()
546 		k = 0; /* start with new decoded frame */  in dsp_bf_decrypt()
550 	dsp->bf_decrypt_in_pos = j;  in dsp_bf_decrypt()
551 	dsp->bf_decrypt_out_pos = k;  in dsp_bf_decrypt()
552 	dsp->bf_sync = sync;  in dsp_bf_decrypt()
590  * The margin of keylen must be 4-56 bytes.
598 	u32 *P = (u32 *)dsp->bf_p;  in dsp_bf_init()
599 	u32 *S = (u32 *)dsp->bf_s;  in dsp_bf_init()
607 		dsp->bf_crypt_out[i] = 0xff;  in dsp_bf_init()
608 		dsp->bf_data_out[i] = dsp_silence;  in dsp_bf_init()
611 	dsp->bf_crypt_pos = 0;  in dsp_bf_init()
612 	dsp->bf_decrypt_in_pos = 0;  in dsp_bf_init()
613 	dsp->bf_decrypt_out_pos = 0;  in dsp_bf_init()
614 	dsp->bf_sync = 0x1ff;  in dsp_bf_init()
615 	dsp->bf_enable = 1;  in dsp_bf_init()
617 	/* Copy the initialization s-boxes */  in dsp_bf_init()
622 	/* Set the p-boxes */  in dsp_bf_init()
666 	dsp->bf_enable = 0;  in dsp_bf_cleanup()