sine wave graphics source wanted

[dale]

Hello,

I am looking for the source code to a program
that will display a sine wave(s) across the middle
of the computer screen. Preferably in C or DOS C,
Anyone know where I could find something like that ?

If you want to e-mail me where I might find source
code like that, thats ok too.

Thank You,
Dale

[Arthur J. O'Dwyer]

On Sun, 29 Feb 2004, dale wrote: I am looking for the source code to a program that will display a sine wave(s) across the middle of the computer screen. Preferably in C or DOS C, Anyone know where I could find something like that ?

Here's some really ancient Turbo C code that implements a
discrete sine algorithm probably stolen from HAKMEM. It
works on my computer. :)
It displays two stationary sine curves: one computed the
ordinary way, and one computed using the HAKMEM method. (They're
very close together.) It wouldn't be too hard to make the
curves move.
As for having the program run on startup: the easiest way
would be to add a line to AUTOEXEC.BAT. ;-)

The code below is free for any and all purposes.

#pragma inline

#include <math.h>
#include <conio.h>

const double pi = 3.1416;

int SineTable[256];

void putpixel(int y, int x, unsigned char col)
{
asm mov ax, 0xA000
asm mov es, ax
asm mov al, col
asm mov bx, y
asm xchg bh, bl /* bx = 256*y */
asm mov di, bx
asm mov cl, 2
asm shr di, cl /* di = 64*y */
asm add di, bx
asm add di, x /* di = 320*y + x */

asm mov [es:di], al
}

void initSines()
{
int s;
int s1 = 0;
int s2 = 402;
register int i;

for (i=0; i < 256; i++)
{
/* s = (2 - 1.0/2048 - 1.0/8192) * s2 - s1;
s1 = s2;
s2 = s;
SineTable[i] = s; */

asm mov ax, s2
asm mov bx, ax
asm shl bx, 1
asm mov cl, 11
asm sar ax, cl
asm sub bx, ax
asm sar ax, 1
asm sar ax, 1
asm add ax, s1
asm sub bx, ax

asm mov ax, s2
asm mov s1, ax
asm mov s2, bx

SineTable[i] = s2;
}
}

int main(void)
{
int i;

asm mov ax, 19
asm int 0x10

initSines();
for (i=0; i < 256; i++)
{
putpixel(100 + sin(i*pi/128) * 100, i, 11);
putpixel(90 + SineTable[i] / 163.84, i, 15);
}

while (!kbhit());
asm mov ax, 3
asm int 0x10
return 0;
}