WaveFile.c

// This file is part of the CircuitPython project: https://circuitpython.org
//
// SPDX-FileCopyrightText: Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include "shared-bindings/audiocore/WaveFile.h"

#include <stdint.h>
#include <string.h>

#include "py/mperrno.h"
#include "py/runtime.h"

#include "shared-module/audiocore/WaveFile.h"

struct wave_format_chunk {
    uint16_t audio_format;
    uint16_t num_channels;
    uint32_t sample_rate;
    uint32_t byte_rate;
    uint16_t block_align;
    uint16_t bits_per_sample;
    uint16_t extra_params; // Assumed to be zero below.
};

void common_hal_audioio_wavefile_construct(audioio_wavefile_obj_t *self,
    pyb_file_obj_t *file,
    uint8_t *buffer,
    size_t buffer_size) {
    // Load the wave
    self->file = file;
    uint8_t chunk_header[16];
    f_rewind(&self->file->fp);
    UINT bytes_read;
    if (f_read(&self->file->fp, chunk_header, 16, &bytes_read) != FR_OK) {
        mp_raise_OSError(MP_EIO);
    }
    if (bytes_read != 16 ||
        memcmp(chunk_header, "RIFF", 4) != 0 ||
        memcmp(chunk_header + 8, "WAVEfmt ", 8) != 0) {
        mp_arg_error_invalid(MP_QSTR_file);
    }
    uint32_t format_size;
    if (f_read(&self->file->fp, &format_size, 4, &bytes_read) != FR_OK) {
        mp_raise_OSError(MP_EIO);
    }
    if (bytes_read != 4 ||
        format_size > sizeof(struct wave_format_chunk)) {
        mp_raise_ValueError(MP_ERROR_TEXT("Invalid format chunk size"));
    }
    struct wave_format_chunk format;
    if (f_read(&self->file->fp, &format, format_size, &bytes_read) != FR_OK) {
        mp_raise_OSError(MP_EIO);
    }
    if (bytes_read != format_size) {
    }

    if (format.audio_format != 1 ||
        format.num_channels > 2 ||
        format.bits_per_sample > 16 ||
        (format_size == 18 &&
         format.extra_params != 0)) {
        mp_raise_ValueError(MP_ERROR_TEXT("Unsupported format"));
    }
    // Get the sample_rate
    self->sample_rate = format.sample_rate;
    self->channel_count = format.num_channels;
    self->bits_per_sample = format.bits_per_sample;

    // TODO(tannewt): Skip any extra chunks that occur before the data section.

    uint8_t data_tag[4];
    if (f_read(&self->file->fp, &data_tag, 4, &bytes_read) != FR_OK) {
        mp_raise_OSError(MP_EIO);
    }
    if (bytes_read != 4 ||
        memcmp((uint8_t *)data_tag, "data", 4) != 0) {
        mp_raise_ValueError(MP_ERROR_TEXT("Data chunk must follow fmt chunk"));
    }

    uint32_t data_length;
    if (f_read(&self->file->fp, &data_length, 4, &bytes_read) != FR_OK) {
        mp_raise_OSError(MP_EIO);
    }
    if (bytes_read != 4) {
        mp_arg_error_invalid(MP_QSTR_file);
    }
    self->file_length = data_length;
    self->data_start = self->file->fp.fptr;

    // Try to allocate two buffers, one will be loaded from file and the other
    // DMAed to DAC.
    if (buffer_size) {
        self->len = buffer_size / 2;
        self->buffer = buffer;
        self->second_buffer = buffer + self->len;
    } else {
        self->len = 256;
        self->buffer = m_malloc(self->len);
        if (self->buffer == NULL) {
            common_hal_audioio_wavefile_deinit(self);
            m_malloc_fail(self->len);
        }

        self->second_buffer = m_malloc(self->len);
        if (self->second_buffer == NULL) {
            common_hal_audioio_wavefile_deinit(self);
            m_malloc_fail(self->len);
        }
    }
}

void common_hal_audioio_wavefile_deinit(audioio_wavefile_obj_t *self) {
    self->buffer = NULL;
    self->second_buffer = NULL;
}

bool common_hal_audioio_wavefile_deinited(audioio_wavefile_obj_t *self) {
    return self->buffer == NULL;
}

uint32_t common_hal_audioio_wavefile_get_sample_rate(audioio_wavefile_obj_t *self) {
    return self->sample_rate;
}

void common_hal_audioio_wavefile_set_sample_rate(audioio_wavefile_obj_t *self,
    uint32_t sample_rate) {
    self->sample_rate = sample_rate;
}

uint8_t common_hal_audioio_wavefile_get_bits_per_sample(audioio_wavefile_obj_t *self) {
    return self->bits_per_sample;
}

uint8_t common_hal_audioio_wavefile_get_channel_count(audioio_wavefile_obj_t *self) {
    return self->channel_count;
}

void audioio_wavefile_reset_buffer(audioio_wavefile_obj_t *self,
    bool single_channel_output,
    uint8_t channel) {
    if (single_channel_output && channel == 1) {
        return;
    }
    // We don't reset the buffer index in case we're looping and we have an odd number of buffer
    // loads
    self->bytes_remaining = self->file_length;
    f_lseek(&self->file->fp, self->data_start);
    self->read_count = 0;
    self->left_read_count = 0;
    self->right_read_count = 0;
}

audioio_get_buffer_result_t audioio_wavefile_get_buffer(audioio_wavefile_obj_t *self,
    bool single_channel_output,
    uint8_t channel,
    uint8_t **buffer,
    uint32_t *buffer_length) {
    if (!single_channel_output) {
        channel = 0;
    }

    uint32_t channel_read_count = self->left_read_count;
    if (channel == 1) {
        channel_read_count = self->right_read_count;
    }

    bool need_more_data = self->read_count == channel_read_count;

    if (self->bytes_remaining == 0 && need_more_data) {
        *buffer = NULL;
        *buffer_length = 0;
        return GET_BUFFER_DONE;
    }

    if (need_more_data) {
        uint32_t num_bytes_to_load = self->len;
        if (num_bytes_to_load > self->bytes_remaining) {
            num_bytes_to_load = self->bytes_remaining;
        }
        UINT length_read;
        if (self->buffer_index % 2 == 1) {
            *buffer = self->second_buffer;
        } else {
            *buffer = self->buffer;
        }
        if (f_read(&self->file->fp, *buffer, num_bytes_to_load, &length_read) != FR_OK || length_read != num_bytes_to_load) {
            return GET_BUFFER_ERROR;
        }
        self->bytes_remaining -= length_read;
        // Pad the last buffer to word align it.
        if (self->bytes_remaining == 0 && length_read % sizeof(uint32_t) != 0) {
            uint32_t pad = length_read % sizeof(uint32_t);
            length_read += pad;
            if (self->bits_per_sample == 8) {
                for (uint32_t i = 0; i < pad; i++) {
                    ((uint8_t *)(*buffer))[length_read / sizeof(uint8_t) - i - 1] = 0x80;
                }
            } else if (self->bits_per_sample == 16) {
                // We know the buffer is aligned because we allocated it onto the heap ourselves.
                #pragma GCC diagnostic push
                #pragma GCC diagnostic ignored "-Wcast-align"
                ((int16_t *)(*buffer))[length_read / sizeof(int16_t) - 1] = 0;
                #pragma GCC diagnostic pop
            }
        }
        *buffer_length = length_read;
        if (self->buffer_index % 2 == 1) {
            self->second_buffer_length = length_read;
        } else {
            self->buffer_length = length_read;
        }
        self->buffer_index += 1;
        self->read_count += 1;
    }

    uint32_t buffers_back = self->read_count - 1 - channel_read_count;
    if ((self->buffer_index - buffers_back) % 2 == 0) {
        *buffer = self->second_buffer;
        *buffer_length = self->second_buffer_length;
    } else {
        *buffer = self->buffer;
        *buffer_length = self->buffer_length;
    }

    if (channel == 0) {
        self->left_read_count += 1;
    } else if (channel == 1) {
        self->right_read_count += 1;
        *buffer = *buffer + self->bits_per_sample / 8;
    }

    return self->bytes_remaining == 0 ? GET_BUFFER_DONE : GET_BUFFER_MORE_DATA;
}

void audioio_wavefile_get_buffer_structure(audioio_wavefile_obj_t *self, bool single_channel_output,
    bool *single_buffer, bool *samples_signed,
    uint32_t *max_buffer_length, uint8_t *spacing) {
    *single_buffer = false;
    // In WAV files, 8-bit samples are always unsigned, and larger samples are always signed.
    *samples_signed = self->bits_per_sample > 8;
    *max_buffer_length = 512;
    if (single_channel_output) {
        *spacing = self->channel_count;
    } else {
        *spacing = 1;
    }
}