| 1 | // g++ -std=c99 -lm $(sdl-config --cflags --libs) synth.cpp -o synth |
| 2 | |
| 3 | #include <stdio.h> |
| 4 | #include <string.h> |
| 5 | #include <wchar.h> |
| 6 | #include <SDL/SDL.h> |
| 7 | #include <SDL/SDL_audio.h> |
| 8 | #include <stdlib.h> |
| 9 | #include <math.h> |
| 10 | |
| 11 | SDL_Surface *screen; |
| 12 | SDL_AudioSpec spec; |
| 13 | Uint32 sound_len; |
| 14 | Uint8 *sound_buffer; |
| 15 | int sound_pos = 0; |
| 16 | int counter; |
| 17 | |
| 18 | //Do all the init stuff |
| 19 | void init_sdl (void) |
| 20 | { |
| 21 | if (SDL_Init (SDL_INIT_VIDEO|SDL_INIT_AUDIO) < 0) |
| 22 | exit (-1); |
| 23 | atexit (SDL_Quit); |
| 24 | screen = SDL_SetVideoMode (640, 480, 16, SDL_HWSURFACE); |
| 25 | if (screen == NULL) |
| 26 | exit (-1); |
| 27 | } |
| 28 | |
| 29 | //Creates the sine wave. To supress ripple, the wave runs continuously by using an incemental counter |
| 30 | void Callback (void *userdata, Uint8 *stream, int len) |
| 31 | { |
| 32 | double pi = 3.1415; |
| 33 | Uint8 *waveptr; |
| 34 | double Hz=50; |
| 35 | double L = 512; |
| 36 | double A = 100; |
| 37 | double SR = 44100; |
| 38 | double F=2*pi*Hz/SR; |
| 39 | |
| 40 | for (int z = 0; z< 512 ; z++) |
| 41 | { |
| 42 | counter++; |
| 43 | sound_buffer[z] = (Uint8) A*sin(F*(double)counter); |
| 44 | } |
| 45 | |
| 46 | //Do the sound loop... |
| 47 | if (sound_pos + len > sound_len) |
| 48 | { |
| 49 | sound_pos=0; |
| 50 | } |
| 51 | |
| 52 | waveptr = sound_buffer + sound_pos; |
| 53 | SDL_MixAudio(stream, waveptr, len, SDL_MIX_MAXVOLUME); |
| 54 | |
| 55 | //stream = waveptr; //Replacing the mixer gives nothing but silence...!?! |
| 56 | |
| 57 | sound_pos += len; |
| 58 | } |
| 59 | |
| 60 | void play (void) |
| 61 | { |
| 62 | sound_buffer = new Uint8[512]; |
| 63 | sound_len= 512; |
| 64 | spec.freq = 44100; |
| 65 | spec.format = AUDIO_S16SYS; |
| 66 | spec.channels = 1; |
| 67 | spec.silence = 0; |
| 68 | spec.samples = 512; |
| 69 | spec.padding = 0; |
| 70 | spec.size = 0; |
| 71 | spec.userdata = 0; |
| 72 | |
| 73 | spec.callback = Callback; |
| 74 | if (SDL_OpenAudio (&spec, NULL) < 0) |
| 75 | { |
| 76 | printf ("Kann audio nicht öffnen: %s\n", SDL_GetError ()); |
| 77 | exit (-1); |
| 78 | } |
| 79 | SDL_PauseAudio (0); |
| 80 | } |
| 81 | |
| 82 | int main(int argc, char* argv[]) |
| 83 | { |
| 84 | init_sdl (); |
| 85 | play (); |
| 86 | SDL_Delay (5000); |
| 87 | return 0; |
| 88 | |
| 89 | } |
| 90 | |