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-common.h"
  16 #include "qemu/fifo8.h"
  17
  18 void fifo8_create(Fifo8 *fifo, uint32_t capacity)
  19 {
  20     fifo->data = g_new(uint8_t, capacity);
  21     fifo->capacity = capacity;
  22     fifo->head = 0;
  23     fifo->num = 0;
  24 }
  25
  26 void fifo8_destroy(Fifo8 *fifo)
  27 {
  28     g_free(fifo->data);
  29 }
  30
  31 void fifo8_push(Fifo8 *fifo, uint8_t data)
  32 {
  33     if (fifo->num == fifo->capacity) {
  34         abort();
  35     }
  36     fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
  37     fifo->num++;
  38 }
  39
  40 void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num)
  41 {
  42     uint32_t start, avail;
  43
  44     if (fifo->num + num > fifo->capacity) {
  45         abort();
  46     }
  47
  48     start = (fifo->head + fifo->num) % fifo->capacity;
  49
  50     if (start + num <= fifo->capacity) {
  51         memcpy(&fifo->data[start], data, num);
  52     } else {
  53         avail = fifo->capacity - start;
  54         memcpy(&fifo->data[start], data, avail);
  55         memcpy(&fifo->data[0], &data[avail], num - avail);
  56     }
  57
  58     fifo->num += num;
  59 }
  60
  61 uint8_t fifo8_pop(Fifo8 *fifo)
  62 {
  63     uint8_t ret;
  64
  65     if (fifo->num == 0) {
  66         abort();
  67     }
  68     ret = fifo->data[fifo->head++];
  69     fifo->head %= fifo->capacity;
  70     fifo->num--;
  71     return ret;
  72 }
  73
  74 const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
  75 {
  76     uint8_t *ret;
  77
  78     if (max == 0 || max > fifo->num) {
  79         abort();
  80     }
  81     *num = MIN(fifo->capacity - fifo->head, max);
  82     ret = &fifo->data[fifo->head];
  83     fifo->head += *num;
  84     fifo->head %= fifo->capacity;
  85     fifo->num -= *num;
  86     return ret;
  87 }
  88
  89 void fifo8_reset(Fifo8 *fifo)
  90 {
  91     fifo->num = 0;
  92     fifo->head = 0;
  93 }
  94
  95 bool fifo8_is_empty(Fifo8 *fifo)
  96 {
  97     return (fifo->num == 0);
  98 }
  99
 100 bool fifo8_is_full(Fifo8 *fifo)
 101 {
 102     return (fifo->num == fifo->capacity);
 103 }
 104
 105 uint32_t fifo8_num_free(Fifo8 *fifo)
 106 {
 107     return fifo->capacity - fifo->num;
 108 }
 109
 110 uint32_t fifo8_num_used(Fifo8 *fifo)
 111 {
 112     return fifo->num;
 113 }
 114
 115 const VMStateDescription vmstate_fifo8 = {
 116     .name = "Fifo8",
 117     .version_id = 1,
 118     .minimum_version_id = 1,
 119     .fields = (VMStateField[]) {
 120         VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, 0, capacity),
 121         VMSTATE_UINT32(head, Fifo8),
 122         VMSTATE_UINT32(num, Fifo8),
 123         VMSTATE_END_OF_LIST()
 124     }
 125 };