simulate the emu10kx's LOG instruct, need help

JoshuaChang · Apr 28, 2011, 02:11 AM

hi,
i'm tring to simulate the emu10kx's LOG instruct using C language, i've read the as10k1 manual and made a rough function, but couldn't get more progress, here is my code:

Code:

int emu10k_log(int x, int exp, int bits) {
    int sign;
    if(x>=0)
        sign=0;
    else
    {
        sign=1;
        x=~x+1;
    }
    while((x&0x80000000)==0 && exp>0)
    {
        x=x<<1;
        exp--;
    }
    if((x&0x80000000)==0x80000000)
        return !sign?(x>>bits&(0x1<<31-bits)-1)+(++exp<<31-bits):~((x>>bits&(0x1<<31-bits)-1)+(++exp<<31-bits))+1;
    if(x<0x1<<31-bits)
        return !sign?x:~x+1;
    while(x>0x1<<31-bits)
        x=x>>1;
    return !sign?x&(0x1<<31-bits)-1:~(x&(0x1<<31-bits)-1)+1;
}

refer to emu10kx's instruct: LOG R, A, X, Y;
x is the A, exp is the X, while bits is the sizeof(X), Y has not been implemented yet.
i have no experience on kx plugin's debug,
some one could give me these instruct's result(on real emu10kx chip)?
LOG R, 0x00012345, 0x7, 0x0;
LOG R, 0x00001234, 0x7, 0x0;
LOG R, 0x00000123, 0x7, 0x0;
LOG R, 0x00000012, 0x7, 0x0;
LOG R, 0x00000001, 0x7, 0x0;
LOG R, 0x40004000, 0x8, 0x0;
LOG R, 0x10001000, 0x8, 0x0;
LOG R, 0x00808000, 0x8, 0x0;
LOG R, 0x00001234, 0x8, 0x0;
LOG R, 0x00000001, 0x8, 0x0;

very thanks~

Max M. · Apr 29, 2011, 03:17 PM

log r, 0x00012345, 0x7, 0; = 0x00123450
log r, 0x00001234, 0x7, 0; = 0x00012340
log r, 0x00000123, 0x7, 0; = 0x00001230
log r, 0x00000012, 0x7, 0; = 0x00000120
log r, 0x00000001, 0x7, 0; = 0x00000010
log r, 0x40004000, 0x8, 0; = 0x40000800
log r, 0x10001000, 0x8, 0; = 0x30000800
log r, 0x00808000, 0x8, 0; = 0x08080000
log r, 0x00001234, 0x8, 0; = 0x00012340
log r, 0x00000001, 0x8, 0; = 0x00000010

(I assume that you understand this C function is provided only for "educational" purposes and should never be used in real code (unless you're writing some emu10kx debugger) - it's inadmissibly suboptimal).

JoshuaChang · Apr 29, 2011, 05:59 PM

wow~Max M!!, you saved my life, big thanks

stylus02 · Apr 29, 2011, 11:34 PM

since the dsp becomes an "old lady" simulating the whole instruction set would be great. we could use our plugins on every pc with asio output.

JoshuaChang · Apr 30, 2011, 05:11 PM

hey stylus02, i'm reading your superspace plugin, in your dsp code, is there any register/constant operand related to frequency? except the control lp_cut=1 and control lp_q=0.3?

stylus02 · Apr 30, 2011, 11:06 PM

now, you mean a control for tweaking the reverb color? there are only static delay times for early an late reverb. you can achieve a coloration over the delay feedback path (reverb decay time & damping (which is simply a lowpass structure)), but this is nothing special. a second lowpass filter affects generally the sound after the delayline. i gave it a feedback additionaly to get more basement. the late reverb is a duplicate of "freeverb" (open source). the sound itselve is very neutral.

https://ccrma.stanford.edu/~jos/pasp/img724.png

http://kxm.dyndns.org/superspace_03.jpg

JoshuaChang · May 1, 2011, 07:07 AM

thanks for the help.
i just want to use the superspace in 44.1khz environment, so any values related to times, frequency should be converted.

stylus02 · May 1, 2011, 09:09 AM

the delay times for comb- and allpassfilters were originally for 44,1 khz. i did no conversions to 48 khz (i had it in mind) because i liked the sound.

btw: if you use my delaylines in a 44,1 khz environment you are closer to jezars "freeverb". this could sound a bit "darker" i fear.
however, the freeverb was tweaked very well, to avoid resonance frequencies. it should sound allways "real".

Apr 28, 2011, 02:11 AM	#1
JoshuaChang HardwareHeaven Lover Join Date: Mar 2003 Posts: 127 Rep Power: 0	simulate the emu10kx's LOG instruct, need help hi, i'm tring to simulate the emu10kx's LOG instruct using C language, i've read the as10k1 manual and made a rough function, but couldn't get more progress, here is my code: Code: int emu10k_log(int x, int exp, int bits) { int sign; if(x>=0) sign=0; else { sign=1; x=~x+1; } while((x&0x80000000)==0 && exp>0) { x=x<<1; exp--; } if((x&0x80000000)==0x80000000) return !sign?(x>>bits&(0x1<<31-bits)-1)+(++exp<<31-bits):~((x>>bits&(0x1<<31-bits)-1)+(++exp<<31-bits))+1; if(x<0x1<<31-bits) return !sign?x:~x+1; while(x>0x1<<31-bits) x=x>>1; return !sign?x&(0x1<<31-bits)-1:~(x&(0x1<<31-bits)-1)+1; } refer to emu10kx's instruct: LOG R, A, X, Y; x is the A, exp is the X, while bits is the sizeof(X), Y has not been implemented yet. i have no experience on kx plugin's debug, some one could give me these instruct's result(on real emu10kx chip)? LOG R, 0x00012345, 0x7, 0x0; LOG R, 0x00001234, 0x7, 0x0; LOG R, 0x00000123, 0x7, 0x0; LOG R, 0x00000012, 0x7, 0x0; LOG R, 0x00000001, 0x7, 0x0; LOG R, 0x40004000, 0x8, 0x0; LOG R, 0x10001000, 0x8, 0x0; LOG R, 0x00808000, 0x8, 0x0; LOG R, 0x00001234, 0x8, 0x0; LOG R, 0x00000001, 0x8, 0x0; very thanks~ __________________ lumetools.blogspot.com

Apr 29, 2011, 03:17 PM	#2
Max M. h/h member-shmember Join Date: Dec 2002 Location: Evil Empire Posts: 2,639 Rep Power: 69	Îòâåò: simulate the emu10kx's LOG instruct, need help log r, 0x00012345, 0x7, 0; = 0x00123450 log r, 0x00001234, 0x7, 0; = 0x00012340 log r, 0x00000123, 0x7, 0; = 0x00001230 log r, 0x00000012, 0x7, 0; = 0x00000120 log r, 0x00000001, 0x7, 0; = 0x00000010 log r, 0x40004000, 0x8, 0; = 0x40000800 log r, 0x10001000, 0x8, 0; = 0x30000800 log r, 0x00808000, 0x8, 0; = 0x08080000 log r, 0x00001234, 0x8, 0; = 0x00012340 log r, 0x00000001, 0x8, 0; = 0x00000010 (I assume that you understand this C function is provided only for "educational" purposes and should never be used in real code (unless you're writing some emu10kx debugger) - it's inadmissibly suboptimal). __________________

Apr 29, 2011, 05:59 PM	Thread Starter #3
JoshuaChang HardwareHeaven Lover Join Date: Mar 2003 Posts: 127 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help wow~Max M!!, you saved my life, big thanks __________________ lumetools.blogspot.com

Apr 29, 2011, 11:34 PM	#4
stylus02 HardwareHeaven Addict Join Date: Jan 2008 Location: germany, sb0090 Posts: 259 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help since the dsp becomes an "old lady" simulating the whole instruction set would be great. we could use our plugins on every pc with asio output. __________________ http://kxm.dyndns.org

Apr 30, 2011, 05:11 PM	Thread Starter #5
JoshuaChang HardwareHeaven Lover Join Date: Mar 2003 Posts: 127 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help hey stylus02, i'm reading your superspace plugin, in your dsp code, is there any register/constant operand related to frequency? except the control lp_cut=1 and control lp_q=0.3? __________________ lumetools.blogspot.com

Apr 30, 2011, 11:06 PM	#6
stylus02 HardwareHeaven Addict Join Date: Jan 2008 Location: germany, sb0090 Posts: 259 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help now, you mean a control for tweaking the reverb color? there are only static delay times for early an late reverb. you can achieve a coloration over the delay feedback path (reverb decay time & damping (which is simply a lowpass structure)), but this is nothing special. a second lowpass filter affects generally the sound after the delayline. i gave it a feedback additionaly to get more basement. the late reverb is a duplicate of "freeverb" (open source). the sound itselve is very neutral. https://ccrma.stanford.edu/~jos/pasp/img724.png http://kxm.dyndns.org/superspace_03.jpg __________________ http://kxm.dyndns.org Last edited by stylus02; Apr 30, 2011 at 11:34 PM.

May 1, 2011, 07:07 AM	Thread Starter #7
JoshuaChang HardwareHeaven Lover Join Date: Mar 2003 Posts: 127 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help thanks for the help. i just want to use the superspace in 44.1khz environment, so any values related to times, frequency should be converted. __________________ lumetools.blogspot.com

May 1, 2011, 09:09 AM	#8
stylus02 HardwareHeaven Addict Join Date: Jan 2008 Location: germany, sb0090 Posts: 259 Rep Power: 0	Re: simulate the emu10kx's LOG instruct, need help the delay times for comb- and allpassfilters were originally for 44,1 khz. i did no conversions to 48 khz (i had it in mind) because i liked the sound. btw: if you use my delaylines in a 44,1 khz environment you are closer to jezars "freeverb". this could sound a bit "darker" i fear. however, the freeverb was tweaked very well, to avoid resonance frequencies. it should sound allways "real". __________________ http://kxm.dyndns.org Last edited by stylus02; May 1, 2011 at 01:32 PM.