portapack-mayhem/firmware/application/io_convert.cpp

103 lines
3.8 KiB
C++

/*
* Copyright (C) 2023 Mark Thompson
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "io_convert.hpp"
#include "complex.hpp"
namespace fs = std::filesystem;
static const fs::path c8_ext = u".C8";
namespace file_convert {
// Convert buffer contents from c16 to c8.
// Same buffer used for input & output; input size is bytes; output size is bytes/2.
void c16_to_c8(const void* buffer, File::Size bytes) {
complex16_t* src = (complex16_t*)buffer;
complex8_t* dest = (complex8_t*)buffer;
// Shift isn't used here because it would amplify noise at center freq since it's a signed number
// i.e. ((-1 >> 8) << 8) = -256, whereas (-1 / 256) * 256 = 0
for (File::Size i = 0; i < bytes / sizeof(complex16_t); i++) {
auto re_out = src[i].real() / 256;
auto im_out = src[i].imag() / 256;
dest[i] = {(int8_t)re_out, (int8_t)im_out};
}
}
// Convert c8 buffer to c16 buffer.
// Same buffer used for input & output; input size is bytes; output size is 2*bytes.
void c8_to_c16(const void* buffer, File::Size bytes) {
complex8_t* src = (complex8_t*)buffer;
complex16_t* dest = (complex16_t*)buffer;
uint32_t i = bytes / sizeof(complex8_t);
if (i != 0) {
do {
i--;
auto re_out = (int16_t)src[i].real() * 256; // C8 to C16 conversion;
auto im_out = (int16_t)src[i].imag() * 256; // Can't shift signed numbers left, so using multiply
dest[i] = {(int16_t)re_out, (int16_t)im_out};
} while (i != 0);
}
}
} /* namespace file_convert */
// Automatically enables C8/C16 conversion based on file extension
Optional<File::Error> FileConvertReader::open(const std::filesystem::path& filename) {
convert_c8_to_c16 = path_iequal(filename.extension(), c8_ext);
return file_.open(filename);
}
// If C8 conversion enabled, half the number of bytes are read from the file & expanded to fill the whole buffer.
File::Result<File::Size> FileConvertReader::read(void* const buffer, const File::Size bytes) {
auto read_result = file_.read(buffer, convert_c8_to_c16 ? bytes / 2 : bytes);
if (read_result.is_ok()) {
if (convert_c8_to_c16) {
file_convert::c8_to_c16(buffer, read_result.value());
read_result = read_result.value() * 2;
}
bytes_read_ += read_result.value();
}
return read_result;
}
// Automatically enables C8/C16 conversion based on file extension
Optional<File::Error> FileConvertWriter::create(const std::filesystem::path& filename) {
convert_c16_to_c8 = path_iequal(filename.extension(), c8_ext);
return file_.create(filename);
}
// If C8 conversion is enabled, half the number of bytes are written to the file.
File::Result<File::Size> FileConvertWriter::write(const void* const buffer, const File::Size bytes) {
if (convert_c16_to_c8) {
file_convert::c16_to_c8(buffer, bytes);
}
auto write_result = file_.write(buffer, convert_c16_to_c8 ? bytes / 2 : bytes);
if (write_result.is_ok()) {
if (convert_c16_to_c8) {
write_result = write_result.value() * 2;
}
bytes_written_ += write_result.value();
}
return write_result;
}