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1 | 355 | bneuman | /** @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 None known.
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8 | */
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9 | |||
10 | #ifndef _RING_BUFFER_H
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11 | #define _RING_BUFFER_H
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12 | |||
13 | /** @brief Creates the struct for a new ring buffer. This just expands to a
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14 | * structure definition and thus should be invoked in the global context.
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15 | *
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16 | * @param struct_name Name of the ring buffer struct.
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17 | *
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18 | * @param size The size of the buffer to create.
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19 | *
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20 | * @param type The type of object that the queue is to hold.
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21 | *
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22 | * @param ... Name or names of the instance or instances of the ring buffer(s)
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23 | * to be created.
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24 | */
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25 | #define RING_BUFFER_NEW(struct_name, size, type, ...) \
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26 | struct struct_name { \
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27 | type queue[size]; \ |
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28 | uint8_t start; \ |
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29 | uint8_t end; \ |
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30 | uint8_t buffer_size; \ |
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31 | } __VA_ARGS__ |
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32 | |||
33 | |||
34 | #define RING_BUFFER_BIT_NEW(struct_name, size, ...) \
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35 | struct struct_name { \
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36 | int8_t queue[(size / 8) + 1]; \ |
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37 | uint16_t start; \ |
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38 | uint16_t end; \ |
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39 | } __VA_ARGS__ |
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40 | |||
41 | /** @brief Initializes the ring buffer, setting its size to the correct value
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42 | *
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43 | * @param buf The ring buffer to initialize.
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44 | *
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45 | * @param size The size of the ring buffer (in array elements)
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46 | */
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47 | #define RING_BUFFER_INIT(buf, size) \
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48 | do { \
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49 | (buf).buffer_size = size; \ |
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50 | } while(0) |
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51 | |||
52 | #define RING_BUFFER_BIT_INIT(buf, size) \
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53 | do { \
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54 | (buf).buffer_size = size; \ |
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55 | } while(0) |
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56 | |||
57 | |||
58 | /** @brief Sets the specified ring buffer to be empty.
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59 | *
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60 | * @param buf The ring buffer to make empty.
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61 | */
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62 | #define RING_BUFFER_CLEAR(buf) \
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63 | do { \
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64 | (buf).start = 0; \
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65 | (buf).end = 0; \
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66 | } while (0) |
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67 | |||
68 | #define RING_BUFFER_BIT_CLEAR(buf) RING_BUFFER_CLEAR(buf)
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69 | /** @brief Returns true if the ring buffer specified is empty.
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70 | *
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71 | * @param buf The buffer to check emptiness of.
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72 | */
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73 | #define RING_BUFFER_EMPTY(buf) ((buf).start == (buf).end)
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74 | |||
75 | |||
76 | |||
77 | #define RING_BUFFER_BIT_EMPTY(buf) RING_BUFFER_EMPTY(buf)
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78 | |||
79 | |||
80 | /** @brief Returns true if the ring buffer specified is full.
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81 | *
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82 | * @param buf The buffer to check fullness of.
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83 | */
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84 | #define RING_BUFFER_FULL(buf) \
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85 | (((buf).end + 1) % (buf).buffer_size == (buf).start)
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86 | |||
87 | #define RING_BUFFER_BIT_FULL(buf) RING_BUFFER_FULL(buf)
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88 | |||
89 | /** @brief Adds val to ring buffer buf. Note that val must be of the type
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90 | * used in creating the ring buffer to prevent the compiler from spewing
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91 | * confusing errors. Also, this assumes that the ring buffer is not full.
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92 | *
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93 | * @param buf The ring buffer to add to.
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94 | * @param val The value to add.
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95 | */
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96 | #define RING_BUFFER_ADD(buf, val) \
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97 | do { \
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98 | (buf).queue[(buf).end] = val; \ |
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99 | (buf).end = ((buf).end + 1) % (buf).buffer_size; \
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100 | } while (0) |
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101 | |||
102 | #define RING_BUFFER_BIT_ADD(buf, val) \
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103 | do { \
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104 | if (val) { \
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105 | (buf).queue[((buf).end >> 3) & 0xff] |= _BV((buf).end & 0x7); \ |
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106 | } \ |
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107 | else { \
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108 | (buf).queue[((buf).end >> 3) & 0xff] &= ~_BV((buf).end & 0x7); \ |
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109 | } \ |
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110 | (buf).end = ((buf).end + 1) % ((buf).buffer_size) << 3); \ |
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111 | } while (0) |
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112 | |||
113 | |||
114 | /** @brief Removes the value at the head of the ring buffer and puts it in
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115 | * val_ret. Note that val_ret must be the same type used in creating the ring
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116 | * buffer to prevent the compiler from spewing confusing errors. Also, this
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117 | * assumes that the ring buffer is not empty.
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118 | *
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119 | * @param buf The ring buffer to remove from.
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120 | * @param val_ret Where to put the value removed from the head of the ring
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121 | * buffer.
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122 | */
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123 | #define RING_BUFFER_REMOVE(buf, val_ret) \
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124 | do { \
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125 | (val_ret) = (buf).queue[(buf).start]; \ |
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126 | (buf).start = ((buf).start + 1) % (buf).buffer_size; \
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127 | } while (0) |
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128 | |||
129 | #define RING_BUFFER_BIT_REMOVE(buf, val_ret) \
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130 | do { \
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131 | (val_ret) = ((buf).queue[((buf).start >> 3) & 0xff] & _BV((buf).start & 0x7)) ? 1 : 0; \ |
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132 | (buf).start = ((buf).start + 1) % ((buf).buffer_size << 3); \ |
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133 | } while (0) |
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134 | |||
135 | /** @brief Checks the value at the head of the ring buffer without removing it
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136 | * and puts it into val_ret. Note that val_ret must be the same type used in
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137 | * creating the ring buffer to prevent the compiler from spewing confusing
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138 | * errors. Also, this assumes that the ring buffer is not empty.
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139 | *
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140 | * @param buf The ring buffer to check from
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141 | * @param val_ret where to put the value checked from the head of the ring
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142 | */
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143 | #define RING_BUFFER_PEEK(buf, val_ret) \
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144 | do { \
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145 | (val_ret) = (buf).queue[(buf).start]; \ |
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146 | } while(0) |
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147 | |||
148 | #endif /* _RING_BUFFER_H */ |