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 const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
  70 {
  71     uint8_t *ret;
  72     uint32_t num;
  73
  74     assert(max > 0 && max <= fifo->num);
  75     num = MIN(fifo->capacity - fifo->head, max);
  76     ret = &fifo->data[fifo->head];
  77     fifo->head += num;
  78     fifo->head %= fifo->capacity;
  79     fifo->num -= num;
  80     if (numptr) {
  81         *numptr = num;
  82     }
  83     return ret;
  84 }
  85
  86 void fifo8_reset(Fifo8 *fifo)
  87 {
  88     fifo->num = 0;
  89     fifo->head = 0;
  90 }
  91
  92 bool fifo8_is_empty(Fifo8 *fifo)
  93 {
  94     return (fifo->num == 0);
  95 }
  96
  97 bool fifo8_is_full(Fifo8 *fifo)
  98 {
  99     return (fifo->num == fifo->capacity);
 100 }
 101
 102 uint32_t fifo8_num_free(Fifo8 *fifo)
 103 {
 104     return fifo->capacity - fifo->num;
 105 }
 106
 107 uint32_t fifo8_num_used(Fifo8 *fifo)
 108 {
 109     return fifo->num;
 110 }
 111
 112 const VMStateDescription vmstate_fifo8 = {
 113     .name = "Fifo8",
 114     .version_id = 1,
 115     .minimum_version_id = 1,
 116     .fields = (const VMStateField[]) {
 117         VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, capacity),
 118         VMSTATE_UINT32(head, Fifo8),
 119         VMSTATE_UINT32(num, Fifo8),
 120         VMSTATE_END_OF_LIST()
 121     }
 122 };