SDL: Initial Audio driver

From e4a80875519617775184e9f6be5ede51772850fa Mon Sep 17 00:00:00 2001
From: Francisco Javier Trujillo Mata <[EMAIL REDACTED]>
Date: Fri, 24 Jun 2022 16:43:20 +0200
Subject: [PATCH] Initial Audio driver

---
 CMakeLists.txt               |   6 ++
 include/SDL_config.h.cmake   |   1 +
 src/audio/SDL_audio.c        |   3 +
 src/audio/SDL_sysaudio.h     |   1 +
 src/audio/ps2/SDL_ps2audio.c | 163 +++++++++++++++++++++++++++++++++++
 src/audio/ps2/SDL_ps2audio.h |  46 ++++++++++
 6 files changed, 220 insertions(+)
 create mode 100644 src/audio/ps2/SDL_ps2audio.c
 create mode 100644 src/audio/ps2/SDL_ps2audio.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1f42cf5f7c5..12d6eced955 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2544,6 +2544,12 @@ elseif(PS2)
   file(GLOB PS2_MAIN_SOURCES ${SDL2_SOURCE_DIR}/src/main/ps2/*.c)
   set(SDLMAIN_SOURCES ${SDLMAIN_SOURCES} ${PS2_MAIN_SOURCES})
 
+  if(SDL_AUDIO)
+    set(SDL_AUDIO_DRIVER_PS2 1)
+    file(GLOB PS2_AUDIO_SOURCES ${SDL2_SOURCE_DIR}/src/audio/ps2/*.c)
+    set(SOURCE_FILES ${SOURCE_FILES} ${PS2_AUDIO_SOURCES})
+    set(HAVE_SDL_AUDIO TRUE)
+  endif()
   if(SDL_FILESYSTEM)
     set(SDL_FILESYSTEM_PS2 1)
     file(GLOB PS2_FILESYSTEM_SOURCES ${SDL2_SOURCE_DIR}/src/filesystem/ps2/*.c)
diff --git a/include/SDL_config.h.cmake b/include/SDL_config.h.cmake
index 129e808d2ab..043817f44d8 100644
--- a/include/SDL_config.h.cmake
+++ b/include/SDL_config.h.cmake
@@ -325,6 +325,7 @@
 #cmakedefine SDL_AUDIO_DRIVER_OS2 @SDL_AUDIO_DRIVER_OS2@
 #cmakedefine SDL_AUDIO_DRIVER_VITA @SDL_AUDIO_DRIVER_VITA@
 #cmakedefine SDL_AUDIO_DRIVER_PSP @SDL_AUDIO_DRIVER_PSP@
+#cmakedefine SDL_AUDIO_DRIVER_PS2 @SDL_AUDIO_DRIVER_PS2@
 
 /* Enable various input drivers */
 #cmakedefine SDL_INPUT_LINUXEV @SDL_INPUT_LINUXEV@
diff --git a/src/audio/SDL_audio.c b/src/audio/SDL_audio.c
index 0ce2ae67b19..3ce3cb9d5e2 100644
--- a/src/audio/SDL_audio.c
+++ b/src/audio/SDL_audio.c
@@ -95,6 +95,9 @@ static const AudioBootStrap *const bootstrap[] = {
 #if SDL_AUDIO_DRIVER_ANDROID
     &ANDROIDAUDIO_bootstrap,
 #endif
+#if SDL_AUDIO_DRIVER_PS2
+    &PS2AUDIO_bootstrap,
+#endif
 #if SDL_AUDIO_DRIVER_PSP
     &PSPAUDIO_bootstrap,
 #endif
diff --git a/src/audio/SDL_sysaudio.h b/src/audio/SDL_sysaudio.h
index 8aa729817ef..d7e1685342e 100644
--- a/src/audio/SDL_sysaudio.h
+++ b/src/audio/SDL_sysaudio.h
@@ -204,6 +204,7 @@ extern AudioBootStrap FUSIONSOUND_bootstrap;
 extern AudioBootStrap aaudio_bootstrap;
 extern AudioBootStrap openslES_bootstrap;
 extern AudioBootStrap ANDROIDAUDIO_bootstrap;
+extern AudioBootStrap PS2AUDIO_bootstrap;
 extern AudioBootStrap PSPAUDIO_bootstrap;
 extern AudioBootStrap VITAAUD_bootstrap;
 extern AudioBootStrap EMSCRIPTENAUDIO_bootstrap;
diff --git a/src/audio/ps2/SDL_ps2audio.c b/src/audio/ps2/SDL_ps2audio.c
new file mode 100644
index 00000000000..daca266cb11
--- /dev/null
+++ b/src/audio/ps2/SDL_ps2audio.c
@@ -0,0 +1,163 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "../../SDL_internal.h"
+
+/* Output audio to nowhere... */
+
+#include "SDL_timer.h"
+#include "SDL_audio.h"
+#include "../SDL_audio_c.h"
+#include "SDL_ps2audio.h"
+
+#include <kernel.h>
+#include <malloc.h>
+#include <audsrv.h>
+#include <ps2_audio_driver.h>
+
+/* The tag name used by PS2 audio */
+#define PS2AUDIO_DRIVER_NAME    "ps2"
+
+static int
+PS2AUDIO_OpenDevice(_THIS, const char *devname)
+{
+    int i, mixlen;
+    struct audsrv_fmt_t format;
+
+    this->hidden = (struct SDL_PrivateAudioData *)
+        SDL_malloc(sizeof(*this->hidden));
+    if (this->hidden == NULL) {
+        return SDL_OutOfMemory();
+    }
+    SDL_zerop(this->hidden);
+
+    /* This is the native supported audio PS2 config  */
+    this->spec.freq = 48000;
+    this->spec.samples = 512;
+    this->spec.channels = 2;
+    this->spec.format = AUDIO_S16LSB;
+
+    SDL_CalculateAudioSpec(&this->spec);
+
+    format.bits     = 16;
+    format.freq     = this->spec.freq;
+    format.channels = this->spec.channels;
+
+    this->hidden->channel = audsrv_set_format(&format);
+    audsrv_set_volume(MAX_VOLUME);
+
+    if (this->hidden->channel < 0) {
+        free(this->hidden->rawbuf);
+        this->hidden->rawbuf = NULL;
+        return SDL_SetError("Couldn't reserve hardware channel");
+    }
+
+    /* Update the fragment size as size in bytes. */
+    SDL_CalculateAudioSpec(&this->spec);
+
+    /* Allocate the mixing buffer.  Its size and starting address must
+       be a multiple of 64 bytes.  Our sample count is already a multiple of
+       64, so spec->size should be a multiple of 64 as well. */
+    mixlen = this->spec.size * NUM_BUFFERS;
+    this->hidden->rawbuf = (Uint8 *) memalign(64, mixlen);
+    if (this->hidden->rawbuf == NULL) {
+        return SDL_SetError("Couldn't allocate mixing buffer");
+    }
+
+    SDL_memset(this->hidden->rawbuf, 0, mixlen);
+    for (i = 0; i < NUM_BUFFERS; i++) {
+        this->hidden->mixbufs[i] = &this->hidden->rawbuf[i * this->spec.size];
+    }
+
+    this->hidden->next_buffer = 0;
+    return 0;
+}
+
+static void PS2AUDIO_PlayDevice(_THIS)
+{
+    uint8_t *mixbuf = this->hidden->mixbufs[this->hidden->next_buffer];
+    audsrv_play_audio((char *)mixbuf, this->spec.size);
+
+    this->hidden->next_buffer = (this->hidden->next_buffer + 1) % NUM_BUFFERS;
+}
+
+/* This function waits until it is possible to write a full sound buffer */
+static void PS2AUDIO_WaitDevice(_THIS)
+{
+    audsrv_wait_audio(this->spec.size);
+}
+
+static Uint8 *PS2AUDIO_GetDeviceBuf(_THIS)
+{
+    return this->hidden->mixbufs[this->hidden->next_buffer];
+}
+
+static void PS2AUDIO_CloseDevice(_THIS)
+{
+    if (this->hidden->channel >= 0) {
+        audsrv_stop_audio();
+        this->hidden->channel = -1;
+    }
+
+    if (this->hidden->rawbuf != NULL) {
+        free(this->hidden->rawbuf);
+        this->hidden->rawbuf = NULL;
+    }
+}
+
+static void PS2AUDIO_ThreadInit(_THIS)
+{
+    /* Increase the priority of this audio thread by 1 to put it
+       ahead of other SDL threads. */
+    int32_t thid;
+    ee_thread_status_t status;
+    thid = GetThreadId();
+    if (ReferThreadStatus(GetThreadId(), &status) == 0) {
+        ChangeThreadPriority(thid, status.current_priority);
+    }
+}
+
+static void PS2AUDIO_Deinitialize(void)
+{
+    deinit_audio_driver();
+}
+
+static SDL_bool PS2AUDIO_Init(SDL_AudioDriverImpl * impl)
+{
+    if(init_audio_driver() < 0)
+        return SDL_FALSE;
+
+    /* Set the function pointers */
+    impl->OpenDevice = PS2AUDIO_OpenDevice;
+    impl->PlayDevice = PS2AUDIO_PlayDevice;
+    impl->WaitDevice = PS2AUDIO_WaitDevice;
+    impl->GetDeviceBuf = PS2AUDIO_GetDeviceBuf;
+    impl->CloseDevice = PS2AUDIO_CloseDevice;
+    impl->ThreadInit = PS2AUDIO_ThreadInit;
+    impl->Deinitialize = PS2AUDIO_Deinitialize;
+    impl->OnlyHasDefaultOutputDevice = SDL_TRUE;
+    return SDL_TRUE;   /* this audio target is available. */
+}
+
+AudioBootStrap PS2AUDIO_bootstrap = {
+    "ps2", "PS2 audio driver", PS2AUDIO_Init, SDL_FALSE
+};
+
+/* vi: set ts=4 sw=4 expandtab: */
diff --git a/src/audio/ps2/SDL_ps2audio.h b/src/audio/ps2/SDL_ps2audio.h
new file mode 100644
index 00000000000..0de2506c282
--- /dev/null
+++ b/src/audio/ps2/SDL_ps2audio.h
@@ -0,0 +1,46 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "../../SDL_internal.h"
+
+#ifndef SDL_ps2audio_h_
+#define SDL_ps2audio_h_
+
+#include "../SDL_sysaudio.h"
+
+/* Hidden "this" pointer for the audio functions */
+#define _THIS   SDL_AudioDevice *this
+
+#define NUM_BUFFERS 2
+
+struct SDL_PrivateAudioData
+{
+   /* The hardware output channel. */
+   int     channel;
+   /* The raw allocated mixing buffer. */
+   Uint8   *rawbuf;
+   /* Individual mixing buffers. */
+   Uint8   *mixbufs[NUM_BUFFERS];
+   /* Index of the next available mixing buffer. */
+   int     next_buffer;
+};
+
+#endif /* SDL_ps2audio_h_ */
+/* vi: set ts=4 sw=4 expandtab: */