PC speaker emulation (Joachim Henke)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1851 c046a42c-6fe2-441c-8c8c-71466251a162

hw/pcspk.c

@@ -0,0 +1,147 @@
+/*
+ * QEMU PC speaker emulation
+ *
+ * Copyright (c) 2006 Joachim Henke
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "vl.h"
+
+#define PCSPK_BUF_LEN 1792
+#define PCSPK_SAMPLE_RATE 32000
+#define PCSPK_MAX_FREQ (PCSPK_SAMPLE_RATE >> 1)
+#define PCSPK_MIN_COUNT ((PIT_FREQ + PCSPK_MAX_FREQ - 1) / PCSPK_MAX_FREQ)
+
+typedef struct {
+    uint8_t sample_buf[PCSPK_BUF_LEN];
+    QEMUSoundCard card;
+    SWVoiceOut *voice;
+    PITState *pit;
+    unsigned int pit_count;
+    unsigned int samples;
+    unsigned int play_pos;
+    int data_on;
+    int dummy_refresh_clock;
+} PCSpkState;
+
+static const char *s_spk = "pcspk";
+static PCSpkState pcspk_state;
+
+static inline void generate_samples(PCSpkState *s)
+{
+    unsigned int i;
+
+    if (s->pit_count) {
+        const uint32_t m = PCSPK_SAMPLE_RATE * s->pit_count;
+        const uint32_t n = ((uint64_t)PIT_FREQ << 32) / m;
+
+        /* multiple of wavelength for gapless looping */
+        s->samples = (PCSPK_BUF_LEN * PIT_FREQ / m * m / (PIT_FREQ >> 1) + 1) >> 1;
+        for (i = 0; i < s->samples; ++i)
+            s->sample_buf[i] = (64 & (n * i >> 25)) - 32;
+    } else {
+        s->samples = PCSPK_BUF_LEN;
+        for (i = 0; i < PCSPK_BUF_LEN; ++i)
+            s->sample_buf[i] = 128; /* silence */
+    }
+}
+
+static void pcspk_callback(void *opaque, int free)
+{
+    PCSpkState *s = opaque;
+    unsigned int n;
+
+    if (pit_get_mode(s->pit, 2) != 3)
+        return;
+
+    n = pit_get_initial_count(s->pit, 2);
+    /* avoid frequencies that are not reproducible with sample rate */
+    if (n < PCSPK_MIN_COUNT)
+        n = 0;
+
+    if (s->pit_count != n) {
+        s->pit_count = n;
+        s->play_pos = 0;
+        generate_samples(s);
+    }
+
+    while (free > 0) {
+        n = audio_MIN(s->samples - s->play_pos, (unsigned int)free);
+        n = AUD_write(s->voice, &s->sample_buf[s->play_pos], n);
+        if (!n)
+            break;
+        s->play_pos = (s->play_pos + n) % s->samples;
+        free -= n;
+    }
+}
+
+int pcspk_audio_init(AudioState *audio)
+{
+    PCSpkState *s = &pcspk_state;
+    audsettings_t as = {PCSPK_SAMPLE_RATE, 1, AUD_FMT_U8};
+
+    if (!audio) {
+        AUD_log(s_spk, "No audio state\n");
+        return -1;
+    }
+    AUD_register_card(audio, s_spk, &s->card);
+
+    s->voice = AUD_open_out(&s->card, s->voice, s_spk, s, pcspk_callback, &as, 0);
+    if (!s->voice) {
+        AUD_log(s_spk, "Could not open voice\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+static uint32_t pcspk_ioport_read(void *opaque, uint32_t addr)
+{
+    PCSpkState *s = opaque;
+    int out;
+
+    s->dummy_refresh_clock ^= (1 << 4);
+    out = pit_get_out(s->pit, 2, qemu_get_clock(vm_clock)) << 5;
+
+    return pit_get_gate(s->pit, 2) | (s->data_on << 1) | s->dummy_refresh_clock | out;
+}
+
+static void pcspk_ioport_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    PCSpkState *s = opaque;
+    const int gate = val & 1;
+
+    s->data_on = (val >> 1) & 1;
+    pit_set_gate(s->pit, 2, gate);
+    if (s->voice) {
+        if (gate) /* restart */
+            s->play_pos = 0;
+        AUD_set_active_out(s->voice, gate & s->data_on);
+    }
+}
+
+void pcspk_init(PITState *pit)
+{
+    PCSpkState *s = &pcspk_state;
+
+    s->pit = pit;
+    register_ioport_read(0x61, 1, 1, pcspk_ioport_read, s);
+    register_ioport_write(0x61, 1, 1, pcspk_ioport_write, s);
+}