https://www.cpcwiki.eu/index.php?action=history&feed=atom&title=Programming%3AFast_16_bit_Square_Root
Programming:Fast 16 bit Square Root - Revision history
2026-08-30T22:21:21Z
Revision history for this page on the wiki
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https://www.cpcwiki.eu/index.php?title=Programming:Fast_16_bit_Square_Root&diff=90908&oldid=prev
Ygdrazil at 08:43, 1 September 2014
2014-09-01T08:43:51Z
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Ygdrazil
https://www.cpcwiki.eu/index.php?title=Programming:Fast_16_bit_Square_Root&diff=18788&oldid=prev
Executioner: Fixed last unroll
2007-09-19T05:22:31Z
<p>Fixed last unroll</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 05:22, 19 September 2007</td>
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Executioner
https://www.cpcwiki.eu/index.php?title=Programming:Fast_16_bit_Square_Root&diff=18787&oldid=prev
Executioner: New page
2007-09-19T05:20:41Z
<p>New page</p>
<p><b>New page</b></p><div>This routine was written by [[User:Executioner|The Executioner]] based on the fast pre-calculated square routine and an algorithm by Milos "baze" Bazelides, with 16 bit arithmetic removed for faster performance.<br />
<br />
The initialisation routine, used to build the squares table (same as for the Pre-calculated Square table (my version)).<br />
<br />
<pre><br />
ld de,1<br />
ld hl,0<br />
ld ix,sqtab<br />
sqloop: ld (ix + 0),l<br />
inc hx<br />
ld (ix + 0),h<br />
dec hx<br />
add hl,de<br />
inc de<br />
inc de<br />
inc lx<br />
jr nz,sqloop<br />
</pre><br />
<br />
The actual 16 bit square root routine.<br />
<br />
'''Input:''' DE = ''The number you want to find the square root of''<br />
<br />
'''Output:''' A = ''Square root of the number supplied in DE''<br />
<br />
'''Destroys:''' HL<br />
<br />
'''Call:''' CALL SqrtDE<br />
<br />
<pre><br />
SqrtDE: ld hl,sqtab + #180<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 6,l<br />
jr nc,$ + 4<br />
res 7,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 5,l<br />
jr nc,$ + 4<br />
res 6,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 4,l<br />
jr nc,$ + 4<br />
res 5,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 3,l<br />
jr nc,$ + 4<br />
res 4,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 2,l<br />
jr nc,$ + 4<br />
res 3,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
set 1,l<br />
jr nc,$ + 4<br />
res 2,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
inc h<br />
inc l<br />
jr nc,$ + 4<br />
res 1,l<br />
<br />
ld a,d<br />
cp (hl)<br />
jr nz,$ + 6<br />
dec h<br />
ld a,e<br />
cp (hl)<br />
ld a,l<br />
ret nc<br />
dec a<br />
ret<br />
</pre></div>
Executioner