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n65/utils/midi/source/helpers.cpp

47 lines
1.1 KiB
C++

#include "helpers.h"
namespace Midi {
////
// I have eliminated any doubt that this function works on variable
// length uintvars up to 4 bytes.
unsigned int read_variable_length(FILE *fp, unsigned int *value_size) {
unsigned int value;
*value_size = 1;
if((value = fgetc(fp)) & 0x80){
unsigned char c;
value &= 0x7F;
do{
(*value_size)++;
value = (value << 7) + ((c = fgetc(fp)) & 0x7F);
} while (c & 0x80);
}
return(value);
}
////
// Swap 4 bytes
int swap_endian_32(int big_endian){
register int little_endian;
little_endian = (big_endian & 0x000000FF);
little_endian = ((big_endian & 0x0000FF00) >> 0x08) | (little_endian << 0x08);
little_endian = ((big_endian & 0x00FF0000) >> 0x10) | (little_endian << 0x08);
little_endian = ((big_endian & 0xFF000000) >> 0x18) | (little_endian << 0x08);
return(little_endian);
}
////
// Swap 2 bytes
short swap_endian_16(short big_endian){
register short little_endian;
little_endian = (big_endian & 0x00FF);
little_endian = ((big_endian & 0xFF00) >> 0x08) | (little_endian << 0x08);
return(little_endian);
}
}