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 "qemu-common.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     if (fifo->num == fifo->capacity) {
  35         abort();
  36     }
  37     fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
  38     fifo->num++;
  39 }
  40
  41 void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num)
  42 {
  43     uint32_t start, avail;
  44
  45     if (fifo->num + num > fifo->capacity) {
  46         abort();
  47     }
  48
  49     start = (fifo->head + fifo->num) % fifo->capacity;
  50
  51     if (start + num <= fifo->capacity) {
  52         memcpy(&fifo->data[start], data, num);
  53     } else {
  54         avail = fifo->capacity - start;
  55         memcpy(&fifo->data[start], data, avail);
  56         memcpy(&fifo->data[0], &data[avail], num - avail);
  57     }
  58
  59     fifo->num += num;
  60 }
  61
  62 uint8_t fifo8_pop(Fifo8 *fifo)
  63 {
  64     uint8_t ret;
  65
  66     if (fifo->num == 0) {
  67         abort();
  68     }
  69     ret = fifo->data[fifo->head++];
  70     fifo->head %= fifo->capacity;
  71     fifo->num--;
  72     return ret;
  73 }
  74
  75 const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
  76 {
  77     uint8_t *ret;
  78
  79     if (max == 0 || max > fifo->num) {
  80         abort();
  81     }
  82     *num = MIN(fifo->capacity - fifo->head, max);
  83     ret = &fifo->data[fifo->head];
  84     fifo->head += *num;
  85     fifo->head %= fifo->capacity;
  86     fifo->num -= *num;
  87     return ret;
  88 }
  89
  90 void fifo8_reset(Fifo8 *fifo)
  91 {
  92     fifo->num = 0;
  93     fifo->head = 0;
  94 }
  95
  96 bool fifo8_is_empty(Fifo8 *fifo)
  97 {
  98     return (fifo->num == 0);
  99 }
 100
 101 bool fifo8_is_full(Fifo8 *fifo)
 102 {
 103     return (fifo->num == fifo->capacity);
 104 }
 105
 106 uint32_t fifo8_num_free(Fifo8 *fifo)
 107 {
 108     return fifo->capacity - fifo->num;
 109 }
 110
 111 uint32_t fifo8_num_used(Fifo8 *fifo)
 112 {
 113     return fifo->num;
 114 }
 115
 116 const VMStateDescription vmstate_fifo8 = {
 117     .name = "Fifo8",
 118     .version_id = 1,
 119     .minimum_version_id = 1,
 120     .fields = (VMStateField[]) {
 121         VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, 0, capacity),
 122         VMSTATE_UINT32(head, Fifo8),
 123         VMSTATE_UINT32(num, Fifo8),
 124         VMSTATE_END_OF_LIST()
 125     }
 126 };