text: #include <string.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include "dsdiff.h"
  #include "endianness.h"
  
  dffinfo init_dffinfo_struct(dsfinfo dsf) {
  	char channelConf[dsf.channels * 4];
  	dffinfo dff;
  	dff.PROPsize = 66 + sizeof(channelConf);
  	dff.DSDsize = dsf.samples / 8 * dsf.channels;
  	dff.FRM8size = 44 + dff.PROPsize + dff.DSDsize;
  
  	return dff;
  }
  
  void dff_channel_conf(char str[], dsfinfo dsf, char hr[]) {
  	switch(dsf.channelConf) {
  		case 1:
  			fputs("Warning: Mono audio is not officialy defined\n", stderr);
  			snprintf(str, 5, "C000"); // next closest thing
  			snprintf(hr, 5, "mono");
  		break;
  		case 2:
  			snprintf(str, 9, "SLFTSRGT");
  			snprintf(hr, 7, "stereo");
  		break;
  		case 3:
  			snprintf(str, 13, "MLFTMRGTC   ");
  			snprintf(hr, 4, "3.0");
  		break;
  		case 4:
  			snprintf(str, 17, "MLFTMRGTLS  RS  ");
  			snprintf(hr, 4, "quad");
  		break;
  		case 5:
  			snprintf(str, 17, "MLFTMRGTC   LFE ");
  			snprintf(hr, 4, "3.1");
  		break;
  		case 6:
  			snprintf(str, 21, "MLFTMRGTC   LS  RS  ");
  			snprintf(hr, 4, "5.0");
  		break;
  		case 7:
  			snprintf(str, 25, "MLFTMRGTC   LFE LS  RS  ");
  			snprintf(hr, 4, "5.1");
  		break;
  		default:
  			fputs("Error: Unrecognized channel configuration\n", stderr);
  			exit(EXIT_FAILURE);
  		break;
  	}
  }
  
  void write_header(FILE** outfile, dsfinfo dsf, dffinfo dff, char* channelStr) {
  	write_FRM8(outfile, dff.FRM8size);
  	write_FVER(outfile);
  	write_PROP(outfile, dff.PROPsize);
  	write_FS(outfile, dsf);
  	write_CHNL(outfile, dsf, channelStr);
  	write_CMPR(outfile);
  }
  
  void write_FRM8(FILE** outfile, uint64_t FRM8size) {
  	fwrite("FRM8", 1, 4, *outfile);
  	uint64_t FRM8size_BE = be_u64(FRM8size);
  	fwrite(&FRM8size_BE, 8, 1, *outfile);
  	fwrite("DSD ", 1, 4, *outfile);
  }
  
  void write_FVER(FILE** outfile) {
  	fwrite("FVER", 1, 4, *outfile);
  	uint64_t FVERsize_BE = be_u64(4);
  	fwrite(&FVERsize_BE, 8, 1, *outfile);
  	uint64_t formatVersion_BE = be_u32(0x01050000);
  	fwrite(&formatVersion_BE, 4, 1, *outfile);
  }
  
  void write_PROP(FILE** outfile, uint64_t PROPsize) {
  	fwrite("PROP", 1, 4, *outfile);
  	uint64_t PROPsize_BE = be_u64(PROPsize);
  	fwrite(&PROPsize_BE, 8, 1, *outfile);
  	fwrite("SND ", 1, 4, *outfile);
  }
  
  void write_FS(FILE** outfile, dsfinfo dsf) {
  	fwrite("FS  ", 1, 4, *outfile);
  	uint64_t FSsize_BE = be_u64(4);
  	fwrite(&FSsize_BE, 8, 1, *outfile);
  	uint32_t fs_BE = be_u32(dsf.fs);
  	fwrite(&fs_BE, 4, 1, *outfile);
  }
  
  void write_CHNL(FILE** outfile, dsfinfo dsf, char channelList[]) {
  	fwrite("CHNL", 1, 4, *outfile);
  	uint64_t CHNLsize_BE = be_u64(2 + dsf.channels * 4);
  	fwrite(&CHNLsize_BE, 8, 1, *outfile);
  	uint16_t chnlCount_BE = be_u16(dsf.channels & 0xffff);
  	fwrite(&chnlCount_BE, 2, 1, *outfile);
  	fwrite(channelList, 1, dsf.channels * 4, *outfile);
  }
  
  void write_CMPR(FILE** outfile) {
  	fwrite("CMPR", 1, 4, *outfile);
  	uint64_t CMPRsize_BE = be_u64(20);
  	fwrite(&CMPRsize_BE, 8, 1, *outfile);
  	fwrite("DSD ", 1, 4, *outfile);
  	uint8_t CMPRchars = 14;
  	fwrite(&CMPRchars, 1, 1, *outfile);
  	fwrite("not compressed\0", 1, CMPRchars + 1, *outfile);
  }
  
  void write_DSD(FILE** infile, FILE** outfile, uint64_t DSDsize, dsfinfo dsf) {
  	fwrite("DSD ", 1, 4, *outfile);
  	uint64_t DSDsize_BE = be_u64(DSDsize);
  	fwrite(&DSDsize_BE, 8, 1, *outfile);
  	convert_DSD_data(infile, outfile, dsf);
  }
  
  void convert_DSD_data(FILE** infile, FILE** outfile, dsfinfo dsf) {
  	const uint8_t bitReverse[] = {
  		0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, 
  		0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 
  		0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 
  		0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 
  		0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 
  		0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
  		0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 
  		0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
  		0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
  		0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, 
  		0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
  		0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
  		0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, 
  		0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
  		0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 
  		0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
  	};
  	fseeko(*infile, 92, SEEK_SET);
  	
  	uint8_t buffer[dsf.channels * dsf.blockSize];
  	uint8_t blocks[dsf.channels][dsf.blockSize];
  	uint64_t b = dsf.samples / 8;
  	uint64_t l;
  	
  	while(b > 0) {
  		if(b > dsf.blockSize) {
  		l = dsf.blockSize;
  		b -= l;
  		} else {
  		l = b;
  		b = 0;
  		}
  		for(int i = 0; i < dsf.channels; i++) {
  			fread(blocks[i], l, 1, *infile);
  		}
  		for(int i=0; i<l*dsf.channels; i+=dsf.channels) {
  			for(int j = 0; j < dsf.channels; j++) {
  				buffer[i + j] = bitReverse[blocks[j][i / dsf.channels]];
  			}
  		}
  		fwrite(buffer, 1, l*dsf.channels, *outfile);
  	}
  }