util/fifo8.c

   1 /*
   2  * Generic FIFO component, implemented as a circular buffer.
   3  *
   4  * Copyright (c) 2012 Peter A. G. Crosthwaite
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  *
  11  * You should have received a copy of the GNU General Public License along
  12  * with this program; if not, see <http://www.gnu.org/licenses/>.
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "migration/vmstate.h"
  17 #include "qemu/fifo8.h"
  18
  19 void fifo8_create(Fifo8 *fifo, uint32_t capacity)
  20 {
  21     fifo->data = g_new(uint8_t, capacity);
  22     fifo->capacity = capacity;
  23     fifo->head = 0;
  24     fifo->num = 0;
  25 }
  26
  27 void fifo8_destroy(Fifo8 *fifo)
  28 {
  29     g_free(fifo->data);
  30 }
  31
  32 void fifo8_push(Fifo8 *fifo, uint8_t data)
  33 {
  34     assert(fifo->num < fifo->capacity);
  35     fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
  36     fifo->num++;
  37 }
  38
  39 void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num)
  40 {
  41     uint32_t start, avail;
  42
  43     assert(fifo->num + num <= fifo->capacity);
  44
  45     start = (fifo->head + fifo->num) % fifo->capacity;
  46
  47     if (start + num <= fifo->capacity) {
  48         memcpy(&fifo->data[start], data, num);
  49     } else {
  50         avail = fifo->capacity - start;
  51         memcpy(&fifo->data[start], data, avail);
  52         memcpy(&fifo->data[0], &data[avail], num - avail);
  53     }
  54
  55     fifo->num += num;
  56 }
  57
  58 uint8_t fifo8_pop(Fifo8 *fifo)
  59 {
  60     uint8_t ret;
  61
  62     assert(fifo->num > 0);
  63     ret = fifo->data[fifo->head++];
  64     fifo->head %= fifo->capacity;
  65     fifo->num--;
  66     return ret;
  67 }
  68
  69 static const uint8_t *fifo8_peekpop_buf(Fifo8 *fifo, uint32_t max,
  70                                         uint32_t *numptr, bool do_pop)
  71 {
  72     uint8_t *ret;
  73     uint32_t num;
  74
  75     assert(max > 0 && max <= fifo->num);
  76     num = MIN(fifo->capacity - fifo->head, max);
  77     ret = &fifo->data[fifo->head];
  78
  79     if (do_pop) {
  80         fifo->head += num;
  81         fifo->head %= fifo->capacity;
  82         fifo->num -= num;
  83     }
  84     if (numptr) {
  85         *numptr = num;
  86     }
  87     return ret;
  88 }
  89
  90 const uint8_t *fifo8_peek_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
  91 {
  92     return fifo8_peekpop_buf(fifo, max, numptr, false);
  93 }
  94
  95 const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
  96 {
  97     return fifo8_peekpop_buf(fifo, max, numptr, true);
  98 }
  99
 100 void fifo8_reset(Fifo8 *fifo)
 101 {
 102     fifo->num = 0;
 103     fifo->head = 0;
 104 }
 105
 106 bool fifo8_is_empty(Fifo8 *fifo)
 107 {
 108     return (fifo->num == 0);
 109 }
 110
 111 bool fifo8_is_full(Fifo8 *fifo)
 112 {
 113     return (fifo->num == fifo->capacity);
 114 }
 115
 116 uint32_t fifo8_num_free(Fifo8 *fifo)
 117 {
 118     return fifo->capacity - fifo->num;
 119 }
 120
 121 uint32_t fifo8_num_used(Fifo8 *fifo)
 122 {
 123     return fifo->num;
 124 }
 125
 126 const VMStateDescription vmstate_fifo8 = {
 127     .name = "Fifo8",
 128     .version_id = 1,
 129     .minimum_version_id = 1,
 130     .fields = (const VMStateField[]) {
 131         VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, capacity),
 132         VMSTATE_UINT32(head, Fifo8),
 133         VMSTATE_UINT32(num, Fifo8),
 134         VMSTATE_END_OF_LIST()
 135     }
 136 };