| 1 | /*************************************************************************** |
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| 2 | * Copyright (c) 2003-2008, Broadcom Corporation |
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| 3 | * All Rights Reserved |
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| 4 | * Confidential Property of Broadcom Corporation |
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| 5 | * |
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| 6 | * THIS SOFTWARE MAY ONLY BE USED SUBJECT TO AN EXECUTED SOFTWARE LICENSE |
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| 7 | * AGREEMENT BETWEEN THE USER AND BROADCOM. YOU HAVE NO RIGHT TO USE OR |
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| 8 | * EXPLOIT THIS MATERIAL EXCEPT SUBJECT TO THE TERMS OF SUCH AN AGREEMENT. |
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| 9 | * |
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| 10 | * $brcm_Workfile: $ |
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| 11 | * $brcm_Revision: $ |
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| 12 | * $brcm_Date: $ |
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| 13 | * |
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| 14 | * Module Description: private message parsing api |
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| 15 | * |
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| 16 | * Revision History: |
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| 17 | * |
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| 18 | * $brcm_Log: $ |
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| 19 | * |
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| 20 | * |
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| 21 | ***************************************************************************/ |
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| 22 | |
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| 23 | #include "bstd.h" |
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| 24 | #include "bdbg.h" |
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| 25 | |
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| 26 | #include "getbits.h" |
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| 27 | |
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| 28 | /* |
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| 29 | Return bit_count of bits from the bitstream. bit_count can be anywhere |
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| 30 | from 0 to 16. The bit_state_t structure has to be reset after 536870911 |
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| 31 | bytes as bindex is 32 bit value. This is not a practical limitation. |
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| 32 | */ |
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| 33 | unsigned int get_bits(size_t bit_count, struct bit_state_t * bs) |
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| 34 | { |
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| 35 | unsigned int bits; |
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| 36 | unsigned char * pbits; |
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| 37 | size_t data_index; |
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| 38 | if(0 == bit_count){ |
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| 39 | return 0; |
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| 40 | } |
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| 41 | data_index = bs->bindex >> 3; |
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| 42 | pbits = &bs->data[data_index]; |
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| 43 | bits = pbits[0]; |
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| 44 | bits <<= 8; |
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| 45 | bits |= pbits[1]; |
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| 46 | bits <<= 8; |
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| 47 | bits |= pbits[2]; |
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| 48 | bits <<= 8; |
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| 49 | bits <<= bs->bindex & 0x7; |
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| 50 | bits >>= (32 - bit_count); |
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| 51 | bs->bindex += bit_count; |
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| 52 | return bits; |
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| 53 | } |
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| 54 | /* Return bit_count of bits from bitstream. bit_count can be anywhere from 0 |
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| 55 | to 32. This function can be called only when bit field to be returned is |
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| 56 | aligned on a byte boundary. Most new standards follow this rule. |
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| 57 | */ |
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| 58 | unsigned int get_bits_aligned(size_t bit_count, struct bit_state_t * bs) |
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| 59 | { |
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| 60 | unsigned int bits; |
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| 61 | unsigned char * pbits; |
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| 62 | size_t data_index; |
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| 63 | |
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| 64 | if(0 == bit_count){ |
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| 65 | return 0; |
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| 66 | } |
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| 67 | BDBG_ASSERT(0 == (bs->bindex & 0x7)); |
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| 68 | data_index = bs->bindex >> 3; |
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| 69 | pbits = &bs->data[data_index]; |
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| 70 | bits = pbits[0]; |
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| 71 | bits <<= 8; |
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| 72 | bits |= pbits[1]; |
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| 73 | bits <<= 8; |
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| 74 | bits |= pbits[2]; |
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| 75 | bits <<= 8; |
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| 76 | bits |= pbits[3]; |
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| 77 | bits >>= (32 - bit_count); |
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| 78 | bs->bindex += bit_count; |
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| 79 | return bits; |
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| 80 | } |
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