edb7d4ba17ad916b5043cc60a986d6fcc421ec66
1 # XXX DO NOT USE, fails on num=65536. wark-wark...
10 if (num
>= res
+ bit
):
12 res
= (res
>> 1) + bit
21 D
= num
# D is input (from num)
25 for i
in range(15, -1, -1): # negative ranges are weird...
29 R
= (R
<<2)|
((D
>>(i
+i
))&3)
30 R
= R
-((Q
<<2)|
1) #/*-Q01*/
34 R
= (R
<<2)|
((D
>>(i
+i
))&3)
35 R
= R
+((Q
<<2)|
3) #/*+Q11*/
38 Q
= (Q
<<1)|
1 #/*new Q:*/
40 Q
= (Q
<<1)|
0 #/*new Q:*/
49 # grabbed these from unit_test_single (convenience, this is just experimenting)
55 return ((x
& 0x7f800000) >> 23) - 127
57 def set_exponent(x
, e
):
58 return (x
& ~
0x7f800000) |
((e
+127) << 23)
61 return ((x
& 0x80000000) >> 31)
63 # convert FP32 to s/e/m
64 def create_fp32(s
, e
, m
):
65 """ receive sign, exponent, mantissa, return FP32 """
66 return set_exponent((s
<< 31) |
get_mantissa(m
))
68 # convert s/e/m to FP32
70 """ receive FP32, return sign, exponent, mantissa """
71 return get_sign(x
), get_exponent(x
), get_mantissa(x
)
74 # main function, takes mantissa and exponent as separate arguments
75 # returns a tuple, sqrt'd mantissa, sqrt'd exponent
77 def main(mantissa
, exponent
):
79 return sqrt(mantissa
<< 1), # shift mantissa up
80 ((exponent
- 1) / 2) # subtract 1 from exp to compensate
81 return sqrt(mantissa
), # mantissa as-is
82 (exponent
/ 2) # no compensating needed on exp
85 if __name__
== '__main__':
86 for Q
in range(1, int(1e7
)):
87 print(Q
, sqrt(Q
), sqrtsimple(Q
), int(Q
**0.5))
88 assert int(Q
**0.5) == sqrtsimple(Q
), "Q sqrtsimpl fail %d" % Q
89 assert int(Q
**0.5) == sqrt(Q
), "Q sqrt fail %d" % Q
92 //This is the main code of integer sqrt function found here:http://verilogcodes.blogspot.com/2017/11/a-verilog-function-for-finding-square-root.html
99 //Verilog function to find square root of a 32 bit number.
100 //The output is 16 bit.
101 function [15:0] sqrt;
102 input [31:0] num; //declare input
103 //intermediate signals.
106 reg [17:0] left,right,r;
109 //initialize all the variables.
113 left = 0; //input to adder/sub
114 right = 0; //input to adder/sub
116 //run the calculations for 16 iterations.
117 for(i=0;i<16;i=i+1) begin
118 right = {q,r[17],1'b1};
119 left = {r[15:0],a[31:30]};
120 a = {a[29:0],2'b00}; //left shift by 2 bits.
121 if (r[17] == 1) //add if r is negative
123 else //subtract if r is positive
125 q = {q[14:0],!r[17]};
127 sqrt = q; //final assignment of output.
129 endfunction //end of Function
132 c version (from paper linked from URL)
134 unsigned squart(D, r) /*Non-Restoring sqrt*/
135 unsigned D; /*D:32-bit unsigned integer to be square rooted */
138 unsigned Q = 0; /*Q:16-bit unsigned integer (root)*/
139 int R = 0; /*R:17-bit integer (remainder)*/
141 for (i = 15;i>=0;i--) /*for each root bit*/
145 R = R<<2)|((D>>(i+i))&3);
146 R = R-((Q<<2)|1); /*-Q01*/
150 R = R<<2)|((D>>(i+i))&3);
151 R = R+((Q<<2)|3); /*+Q11*/
153 if (R>=0) Q = Q<<1)|1; /*new Q:*/
154 else Q = Q<<1)|0; /*new Q:*/
157 /*remainder adjusting*/
158 if (R<0) R = R+((Q<<1)|1);
159 *r = R; /*return remainder*/
160 return(Q); /*return root*/
165 short isqrt(short num) {
167 short bit = 1 << 14; // The second-to-top bit is set: 1 << 30 for 32 bits
169 // "bit" starts at the highest power of four <= the argument.
174 if (num >= res + bit) {
176 res = (res >> 1) + bit;