Accessing SIN/COS tables in SPIN
Javalin
Posts: 892
Hello all,
Is there some example code available for accessing the sine/cosine tables via SPIN?
I've looked in the manual, and some of the float examples/library's
Particuarly I am after SIN functions
Cheers
James
Is there some example code available for accessing the sine/cosine tables via SPIN?
I've looked in the manual, and some of the float examples/library's
Particuarly I am after SIN functions
Cheers
James
Comments
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Ken - The floating point object is ASM only.....
Cheers both,
James
http://forums.parallax.com/showthread.php?p=606978
There are a couple of versions, both spin and asm.
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Tracy Allen
www.emesystems.com
PUB sin(angle) : s | c,z c := angle & $800 'angle: 0..8192 = 360° z := angle & $1000 if c angle := -angle angle |= $E000>>1 angle <<= 1 s := word[noparse][[/noparse]angle] if z s := -s ' return sin = -$FFFF..+$FFFFAndy
Thanks!!!!!
James
Couple of possibly silly questions if I may!
1) If I am passing an angle in degrees to the "fullsine" function - do I need to * 22 to get the 0-8192 = 0-360 resolution? I guess so?
2) Is there an easy way of converting the 2's complement output to a decimal distance (+ or -) ??
My Math is rubbish - sorry!
Cheers,
James
PUB sin(degree, range) : s | c,z,angle angle := (degree*91)~>2 ' *22.75 c := angle & $800 z := angle & $1000 if c angle := -angle angle |= $E000>>1 angle <<= 1 s := word[noparse][[/noparse]angle] if z s := -s return (s*range)~>16 ' return sin = -range..+rangeAndy
Post Edited (Ariba) : 5/20/2008 3:38:55 PM GMT
Sorry - Im not sure what the range parameter here is doing? Can you give an example?
James
Using Tracy's fullsine function to find the opposite on a triangle, I do the following and I get:
· "result a=682 hyp=5 sine=44 opp=220"
Sure Im doing something really stupid but also·really struggling to get my head around this one.
According to excel (and my drawing) I should get:
· Hyp = 6 (actually 5.8 but rounded)
· Sine·= 0.515 ish
··Opposite is 3.
Cheers all
James
' work out the Hypot distX := 3 distY := 5 mdLatDistance := ^^((distX*distX)+(distY*distY)) ' angle is 31 degree's. so my Opposite should be 3 ish angle1 := 31 * 22 mdLatSine := fullsine(||angle1) / 728 mdLatResult := mdLatSine * mdLatDistance ' debug the results debug.str(string("result a=")) debug.dec(angle1) debug.str(string(" hyp=")) debug.dec(mdLatDistance) debug.str(string(" sine=")) debug.dec(mdlatsine) debug.str(string(" opp=")) debug.dec(mdlatresult) debug.putc(13) ' the following PRI takes the angle as input and looks up the sine of the angle in the HUB rom sine table ' The input angle is 0 to 8181 corresponding to 0 to 360 degrees or 0 to 2 pi radians ' The result is a twos complement number in the range of +/- 65535, representing + and minus 1. PRI fullsine(x) | y, q ' x is 0 to 2^13 (0 to 8191) for 0 to 360 degrees q := x >> 11 ' two highest bits of 13 are the quadrant, 0, 1, 2 or 3 y := (x & $7ff) << 1 ' 0 to 90- degrees, are contained in 11 bits, shift left one for Word offset ' this is the address offset into the sine table in hub rom ' note: the parentheses are important for operator precedence case q ' select quadrant 0,1,2,3 0 : result := word[noparse][[/noparse]$E000 + y] 1 : result := word[noparse][[/noparse]$F000 - y] ' 2049 angles, 16 bit sin(angle) values corresponding 0 to 90 degrees. 2 : result := -word[noparse][[/noparse]$E000 + y] ' the same table is folded over and mirrored for all 360 degrees 3 : result := -word[noparse][[/noparse]$F000 - y] ' value returned in the range of -$ffff to +$ffff return resultPost Edited (Javalin) : 5/21/2008 5:11:26 PM GMT
with the function above: sin(x,1000) gives a result from -1000 to +1000, sin(x,256) results in -256..+256
with concrete numbers:
sin(0,1000) = 0, sin(45,1000) = 707, sin(90,1000) = 1000 and so on...
Here is an example that uses sin and cos to draw circles on PropTerminal:
{{ Draw a Circle on PropTerminal }} CON _clkmode = xtal1 + pll16x _xinfreq = 5_000_000 OBJ term : "PC_Interface" PUB Main term.start(31,30) 'start the interface repeat until term.abs_x > 0 'wait until mouse over Terminal circle(100,50,30) circle(150,80,50) circle(200,20,10) repeat PUB circle(x,y,radius) | i repeat i from 0 to 360 'draw circle term.plot(x+sin(i,radius), y+cos(i,radius)) PUB sin(degree, range) : s | c,z,angle angle := (degree*91)~>2 ' *22.75 c := angle & $800 z := angle & $1000 if c angle := -angle angle |= $E000>>1 angle <<= 1 s := word[noparse][[/noparse]angle] if z s := -s return (s*range)~>16 ' return sin = -range..+range PUB cos(degree,range) return sin(degree+90,range)Andy
Thanks!
james