01 minialsa 架构与轻量级 PCM 抽象¶

/* 音频传输方向 */
typedef enum {
    AOS_PCM_STREAM_PLAYBACK = 0,
    AOS_PCM_STREAM_CAPTURE  = 1,
} aos_pcm_stream_t;

/* PCM 硬件参数配置 */
typedef struct {
    uint32_t rate;          /* 采样率: 8000, 16000, 44100, 48000 Hz */
    uint16_t channels;      /* 声道数: 1 (Mono), 2 (Stereo) */
    uint16_t format;        /* 位深: 16-bit, 24-bit, 32-bit PCM */
    uint32_t period_size;   /* 单个周期帧数 (Frames per Period) */
    uint32_t period_count;  /* 周期个数 (通常 2 ~ 4，构成双缓冲或多缓冲) */
} aos_pcm_hw_params_t;

/* PCM 操作接口抽象表 (类似 Linux ASoC platform/dai driver) */
struct aos_pcm_ops {
    int (*open)(aos_pcm_t *pcm);
    int (*close)(aos_pcm_t *pcm);
    int (*hw_params)(aos_pcm_t *pcm, aos_pcm_hw_params_t *params);
    int (*prepare)(aos_pcm_t *pcm);
    int (*start)(aos_pcm_t *pcm);
    int (*stop)(aos_pcm_t *pcm);
    int (*drain)(aos_pcm_t *pcm);
    int (*pause)(aos_pcm_t *pcm, int enable);
    int (*write)(aos_pcm_t *pcm, const void *buf, size_t size);
    int (*read)(aos_pcm_t *pcm, void *buf, size_t size);
};

/* PCM 实例化句柄 */
struct aos_pcm {
    char                name[16];        /* 设备名称: "pcmC0D0p", "default" */
    aos_pcm_stream_t    stream;          /* 播放还是录音 */
    int                 mode;            /* 阻塞模式 (0) 或 非阻塞模式 (NONBLOCK) */
    aos_pcm_hw_params_t hw_params;       /* 当前生效的硬件参数 */
    struct aos_pcm_ops *ops;             /* 绑定的硬件操作接口表 */
    void               *private_data;    /* 指向底层 I2S/DMA 驱动私有句柄 */
    ringbuffer_t        ring_buf;        /* 环形缓冲区 (可选软件平滑缓冲) */
    void               *sem_wait;        /* RTOS 唤醒二值信号量 */
    volatile int        state;           /* PCM 状态: STOP, RUNNING, XRUN, PAUSE */
};

#include <stdint.h>
#include <stdbool.h>
#include "FreeRTOS.h"
#include "semphr.h"

/* 状态定义 */
#define PCM_STATE_IDLE     0
#define PCM_STATE_RUNNING  1
#define PCM_STATE_PAUSED   2

int aos_pcm_open(aos_pcm_t **pcm_handle, const char *name,
                 aos_pcm_stream_t stream, int mode)
{
    aos_pcm_t *pcm = (aos_pcm_t *)pvPortMalloc(sizeof(aos_pcm_t));
    if (!pcm) return -1;

    memset(pcm, 0, sizeof(aos_pcm_t));
    strncpy(pcm->name, name, sizeof(pcm->name) - 1);
    pcm->stream = stream;
    pcm->mode = mode;
    pcm->state = PCM_STATE_IDLE;

    /* 创建唤醒信号量 (初始为 1) */
    pcm->sem_wait = xSemaphoreCreateBinary();
    xSemaphoreGive(pcm->sem_wait);

    /* 绑定硬件操作集 (根据设备名绑定对应的芯片 BSP 驱动) */
    pcm->ops = hal_get_i2s_pcm_ops();
    if (pcm->ops && pcm->ops->open) {
        pcm->ops->open(pcm);
    }

    *pcm_handle = pcm;
    return 0;
}

int aos_pcm_write(aos_pcm_t *pcm, const void *buf, size_t size)
{
    if (!pcm || !buf || size == 0) return -1;

    size_t written = 0;
    while (written < size) {
        /* 调用底层硬件驱动写入接口 */
        int ret = pcm->ops->write(pcm, (uint8_t *)buf + written, size - written);
        if (ret > 0) {
            written += ret;
            if (pcm->state != PCM_STATE_RUNNING) {
                pcm->ops->start(pcm);
                pcm->state = PCM_STATE_RUNNING;
            }
        } else if (ret == 0) {
            /* 硬件缓冲区满 */
            if (pcm->mode == 1 /* NONBLOCK */) {
                return written > 0 ? written : -11; /* EAGAIN */
            }
            /* 阻塞等待 DMA ISR 唤醒，超时时间设为 100ms */
            if (xSemaphoreTake(pcm->sem_wait, pdMS_TO_TICKS(100)) != pdTRUE) {
                /* 超时严重错误：DMA 停止工作或时钟丢失 */
                return -1;
            }
        } else {
            return ret; /* 硬件错误 */
        }
    }
    return written;
}

/* 芯片外设 DMA 中断服务程序 (ISR) 回调 */
void hal_i2s_dma_irq_handler(void *arg)
{
    aos_pcm_t *pcm = (aos_pcm_t *)arg;
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;

    /* 唤醒阻塞在 write 的音频任务 */
    if (pcm && pcm->sem_wait) {
        xSemaphoreGiveFromISR(pcm->sem_wait, &xHigherPriorityTaskWoken);
        portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
    }
}