1 | /**************************************************************************
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2 | *
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3 | * bitio_m_mems.h -- Macros for bitio to memory (random access)
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4 | * Copyright (C) 1994 Neil Sharman
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5 | *
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6 | * This program is free software; you can redistribute it and/or modify
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7 | * it under the terms of the GNU General Public License as published by
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8 | * the Free Software Foundation; either version 2 of the License, or
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9 | * (at your option) any later version.
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10 | *
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11 | * This program is distributed in the hope that it will be useful,
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | * GNU General Public License for more details.
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15 | *
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16 | * You should have received a copy of the GNU General Public License
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17 | * along with this program; if not, write to the Free Software
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18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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19 | *
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20 | **************************************************************************
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21 | *
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22 | * This file contains macros for doing bitwise input and output on an array
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23 | * of chars. These routines are slower than the ones in "mem" files. but
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24 | * with these routines you can mix reads and writes, or multiple writes, on
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25 | * the array of chars at the same time and guarantee them to work, also you
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26 | * can seek to a point and do a write. The decode and encode macros cannot
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27 | * detect when the end off the character is reached and just continue
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28 | * processing.
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29 | *
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30 | **************************************************************************/
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31 |
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32 | #ifndef H_BITIO_M_MEMS
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33 | #define H_BITIO_M_MEMS
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34 |
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35 | typedef struct mems_bitio_state
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36 | {
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37 | unsigned char *Base;
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38 | unsigned long pos;
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39 | }
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40 | mems_bitio_state;
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41 |
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42 |
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43 | #define ENCODE_START(b,p) \
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44 | { \
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45 | register unsigned char *__base = b; \
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46 | register unsigned long __pos = p;
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47 |
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48 | #define ENCODE_CONTINUE(b) \
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49 | { \
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50 | register unsigned char *__base = (b).Base; \
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51 | register unsigned long __pos = (b).pos;
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52 |
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53 | #define ENCODE_BIT(b) \
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54 | do { \
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55 | if (b) \
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56 | __base[__pos>>3] |= 0x80 >> (__pos&7); \
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57 | else \
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58 | __base[__pos>>3] &= 0xff7f >> (__pos&7); \
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59 | __pos++; \
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60 | } while(0)
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61 |
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62 | #define ENCODE_PAUSE(b) \
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63 | (b).Base = __base; \
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64 | (b).pos = __pos; \
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65 | }
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66 |
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67 | #define ENCODE_FLUSH
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68 |
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69 |
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70 | #define ENCODE_DONE \
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71 | ENCODE_FLUSH; \
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72 | }
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73 |
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74 |
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75 | #define DECODE_START(b,p) \
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76 | { \
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77 | register unsigned char *__base = b; \
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78 | register unsigned long __pos = p;
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79 |
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80 | #define DECODE_CONTINUE(b) \
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81 | { \
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82 | register unsigned char *__base = (b).Base; \
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83 | register unsigned long __pos = (b).pos;
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84 |
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85 | #define DECODE_ADD_FF(b) \
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86 | do { \
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87 | (b) += (b) + (__base[__pos>>3] & (0x80 >> (__pos&7)) != 0); \
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88 | __pos++; \
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89 | } while(0)
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90 |
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91 | #define DECODE_ADD_00(b) DECODE_ADD_FF(b)
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92 |
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93 | #define DECODE_BIT \
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94 | (__pos++, ((__base[(__pos-1)>>3] & (0x80 >> ((__pos-1)&7))) != 0))
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95 |
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96 | #define DECODE_DONE ; \
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97 | }
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98 |
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99 | #define DECODE_PAUSE(b) \
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100 | (b).Base = __base; \
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101 | (b).pos = __pos; \
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102 | }
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103 |
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104 | #define DECODE_SEEK(pos) __pos = (pos)
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105 |
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106 | #define ENCODE_SEEK(pos) __pos = (pos)
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107 |
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108 |
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109 |
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110 |
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111 |
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112 | #endif
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