root / trunk / code / lib / include / libdragonfly / ring_buffer.h @ 88
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1 | 88 | bcoltin | /** @file Include macros to create a ring buffer. Originally written for 15-410.
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2 | * Modified for use in ATMega128 serial driver
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3 | *
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4 | * @author Cornell Wright (cgwright)
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5 | * @author Jason P. Winters (jpwinter)
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6 | *
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7 | * @bugs Could not create buffer of non byte-sized elements due to modding with sizeof(queue).
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8 | * Fixed 3/2/07, Felix Duvallet and Brad Neuman
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9 | */
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10 | |||
11 | #ifndef _RING_BUFFER_H
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12 | #define _RING_BUFFER_H
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13 | |||
14 | /** @brief Creates the struct for a new ring buffer. This just expands to a
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15 | * structure definition and thus should be invoked in the global context.
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16 | *
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17 | * @param struct_name Name of the ring buffer struct.
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18 | *
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19 | * @param size The size of the buffer to create.
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20 | *
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21 | * @param type The type of object that the queue is to hold.
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22 | *
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23 | * @param ... Name or names of the instance or instances of the ring buffer(s)
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24 | * to be created.
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25 | */
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26 | #define RING_BUFFER_NEW(struct_name, size, type, ...) \
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27 | struct struct_name { \
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28 | type queue[size]; \ |
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29 | uint8_t start; \ |
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30 | uint8_t end; \ |
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31 | uint8_t buffer_size; \ |
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32 | } __VA_ARGS__ |
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33 | |||
34 | |||
35 | /** @brief Initializes the ring buffer, setting its size to the correct value
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36 | *
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37 | * @param buf The ring buffer to initialize.
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38 | *
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39 | * @param size The size of the ring buffer (in array elements)
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40 | */
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41 | #define RING_BUFFER_INIT(buf, size) \
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42 | do { \
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43 | (buf).buffer_size = size; \ |
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44 | } while(0) |
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45 | |||
46 | |||
47 | /** @brief Sets the specified ring buffer to be empty.
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48 | *
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49 | * @param buf The ring buffer to make empty.
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50 | */
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51 | #define RING_BUFFER_CLEAR(buf) \
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52 | do { \
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53 | (buf).start = 0; \
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54 | (buf).end = 0; \
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55 | } while (0) |
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56 | |||
57 | /** @brief Returns true if the ring buffer specified is empty.
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58 | *
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59 | * @param buf The buffer to check emptiness of.
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60 | */
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61 | #define RING_BUFFER_EMPTY(buf) ((buf).start == (buf).end)
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62 | |||
63 | |||
64 | /** @brief Returns true if the ring buffer specified is full.
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65 | *
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66 | * @param buf The buffer to check fullness of.
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67 | */
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68 | #define RING_BUFFER_FULL(buf) \
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69 | (((buf).end + 1) % (buf).buffer_size == (buf).start)
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70 | |||
71 | |||
72 | /** @brief Adds val to ring buffer buf. Note that val must be of the type
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73 | * used in creating the ring buffer to prevent the compiler from spewing
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74 | * confusing errors. Also, this assumes that the ring buffer is not full.
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75 | *
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76 | * @param buf The ring buffer to add to.
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77 | * @param val The value to add.
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78 | */
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79 | #define RING_BUFFER_ADD(buf, val) \
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80 | do { \
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81 | (buf).queue[(buf).end] = val; \ |
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82 | (buf).end = ((buf).end + 1) % (buf).buffer_size; \
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83 | } while (0) |
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84 | |||
85 | |||
86 | /** @brief Removes the value at the head of the ring buffer and puts it in
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87 | * val_ret. Note that val_ret must be the same type used in creating the ring
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88 | * buffer to prevent the compiler from spewing confusing errors. Also, this
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89 | * assumes that the ring buffer is not empty.
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90 | *
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91 | * @param buf The ring buffer to remove from.
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92 | * @param val_ret Where to put the value removed from the head of the ring
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93 | * buffer.
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94 | */
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95 | #define RING_BUFFER_REMOVE(buf, val_ret) \
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96 | do { \
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97 | (val_ret) = (buf).queue[(buf).start]; \ |
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98 | (buf).start = ((buf).start + 1) % (buf).buffer_size; \
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99 | } while (0) |
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100 | |||
101 | /** @brief Checks the value at the head of the ring buffer without removing it
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102 | * and puts it into val_ret. Note that val_ret must be the same type used in
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103 | * creating the ring buffer to prevent the compiler from spewing confusing
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104 | * errors. Also, this assumes that the ring buffer is not empty.
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105 | *
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106 | * @param buf The ring buffer to check from
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107 | * @param val_ret where to put the value checked from the head of the ring
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108 | */
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109 | #define RING_BUFFER_PEEK(buf, val_ret) \
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110 | do { \
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111 | (val_ret) = (buf).queue[(buf).start]; \ |
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112 | } while(0) |
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113 | |||
114 | #endif /* _RING_BUFFER_H */ |