hw/pcspk.c

   1 /*
   2  * QEMU PC speaker emulation
   3  *
   4  * Copyright (c) 2006 Joachim Henke
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "hw.h"
  26 #include "pc.h"
  27 #include "isa.h"
  28 #include "audio/audio.h"
  29 #include "qemu-timer.h"
  30
  31 #define PCSPK_BUF_LEN 1792
  32 #define PCSPK_SAMPLE_RATE 32000
  33 #define PCSPK_MAX_FREQ (PCSPK_SAMPLE_RATE >> 1)
  34 #define PCSPK_MIN_COUNT ((PIT_FREQ + PCSPK_MAX_FREQ - 1) / PCSPK_MAX_FREQ)
  35
  36 typedef struct {
  37     uint8_t sample_buf[PCSPK_BUF_LEN];
  38     QEMUSoundCard card;
  39     SWVoiceOut *voice;
  40     ISADevice *pit;
  41     unsigned int pit_count;
  42     unsigned int samples;
  43     unsigned int play_pos;
  44     int data_on;
  45     int dummy_refresh_clock;
  46 } PCSpkState;
  47
  48 static const char *s_spk = "pcspk";
  49 static PCSpkState pcspk_state;
  50
  51 static inline void generate_samples(PCSpkState *s)
  52 {
  53     unsigned int i;
  54
  55     if (s->pit_count) {
  56         const uint32_t m = PCSPK_SAMPLE_RATE * s->pit_count;
  57         const uint32_t n = ((uint64_t)PIT_FREQ << 32) / m;
  58
  59         /* multiple of wavelength for gapless looping */
  60         s->samples = (PCSPK_BUF_LEN * PIT_FREQ / m * m / (PIT_FREQ >> 1) + 1) >> 1;
  61         for (i = 0; i < s->samples; ++i)
  62             s->sample_buf[i] = (64 & (n * i >> 25)) - 32;
  63     } else {
  64         s->samples = PCSPK_BUF_LEN;
  65         for (i = 0; i < PCSPK_BUF_LEN; ++i)
  66             s->sample_buf[i] = 128; /* silence */
  67     }
  68 }
  69
  70 static void pcspk_callback(void *opaque, int free)
  71 {
  72     PCSpkState *s = opaque;
  73     unsigned int n;
  74
  75     if (pit_get_mode(s->pit, 2) != 3)
  76         return;
  77
  78     n = pit_get_initial_count(s->pit, 2);
  79     /* avoid frequencies that are not reproducible with sample rate */
  80     if (n < PCSPK_MIN_COUNT)
  81         n = 0;
  82
  83     if (s->pit_count != n) {
  84         s->pit_count = n;
  85         s->play_pos = 0;
  86         generate_samples(s);
  87     }
  88
  89     while (free > 0) {
  90         n = audio_MIN(s->samples - s->play_pos, (unsigned int)free);
  91         n = AUD_write(s->voice, &s->sample_buf[s->play_pos], n);
  92         if (!n)
  93             break;
  94         s->play_pos = (s->play_pos + n) % s->samples;
  95         free -= n;
  96     }
  97 }
  98
  99 int pcspk_audio_init(ISABus *bus)
 100 {
 101     PCSpkState *s = &pcspk_state;
 102     struct audsettings as = {PCSPK_SAMPLE_RATE, 1, AUD_FMT_U8, 0};
 103
 104     AUD_register_card(s_spk, &s->card);
 105
 106     s->voice = AUD_open_out(&s->card, s->voice, s_spk, s, pcspk_callback, &as);
 107     if (!s->voice) {
 108         AUD_log(s_spk, "Could not open voice\n");
 109         return -1;
 110     }
 111
 112     return 0;
 113 }
 114
 115 static uint32_t pcspk_ioport_read(void *opaque, uint32_t addr)
 116 {
 117     PCSpkState *s = opaque;
 118     int out;
 119
 120     s->dummy_refresh_clock ^= (1 << 4);
 121     out = pit_get_out(s->pit, 2, qemu_get_clock_ns(vm_clock)) << 5;
 122
 123     return pit_get_gate(s->pit, 2) | (s->data_on << 1) | s->dummy_refresh_clock | out;
 124 }
 125
 126 static void pcspk_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 127 {
 128     PCSpkState *s = opaque;
 129     const int gate = val & 1;
 130
 131     s->data_on = (val >> 1) & 1;
 132     pit_set_gate(s->pit, 2, gate);
 133     if (s->voice) {
 134         if (gate) /* restart */
 135             s->play_pos = 0;
 136         AUD_set_active_out(s->voice, gate & s->data_on);
 137     }
 138 }
 139
 140 void pcspk_init(ISADevice *pit)
 141 {
 142     PCSpkState *s = &pcspk_state;
 143
 144     s->pit = pit;
 145     register_ioport_read(0x61, 1, 1, pcspk_ioport_read, s);
 146     register_ioport_write(0x61, 1, 1, pcspk_ioport_write, s);
 147 }