move normalise function, add lowbits param, call it

[ieee754fpu.git] / src / add / fsqrt.py

diff --git a/src/add/fsqrt.py b/src/add/fsqrt.py
index c88aea3991f119b29a9415396292ddf64d626773..02449b0f75b41b0ba2e004711d9570ccca49ca3d 100644 (file)
--- a/src/add/fsqrt.py
+++ b/src/add/fsqrt.py
@@ -22,31 +22,25 @@ def sqrtsimple(num):
 
 def sqrt(num):
     D = num # D is input (from num)
-    Q = 0
-    R = 0
-    r = 0 # remainder
+    Q = 0 # quotient
+    R = 0 # remainder
     for i in range(64, -1, -1): # negative ranges are weird...
 
-        if (R>=0):
-
-            R = (R<<2)|((D>>(i+i))&3)
-            R = R-((Q<<2)|1) #/*-Q01*/
+        R = (R<<2)|((D>>(i+i))&3)
 
+        if R >= 0:
+            R -= ((Q<<2)|1) # -Q01
         else:
+            R += ((Q<<2)|3) # +Q11
 
-            R = (R<<2)|((D>>(i+i))&3)
-            R = R+((Q<<2)|3) #/*+Q11*/
-
-        if (R>=0):
-            Q = (Q<<1)|1 #/*new Q:*/
-        else:
-            Q = (Q<<1)|0 #/*new Q:*/
+        Q <<= 1
+        if R >= 0:
+            Q |= 1 # new Q
 
+    if R < 0:
+        R = R + ((Q<<1)|1)
 
-    if (R<0):
-        R = R+((Q<<1)|1)
-        r = R
-    return Q, r
+    return Q, R
 
 
 # grabbed these from unit_test_single (convenience, this is just experimenting)
@@ -86,6 +80,15 @@ def main(mantissa, exponent):
     return m, r, exponent >> 1
 
 
+#normalization function
+def normalise(s, m, e, lowbits):
+    if (lowbits >= 2):
+        m += 1
+    if get_mantissa(m) == ((1<<24)-1):
+        e += 1
+    return s, m, e
+
+
 def fsqrt_test(x):
 
     xbits = x.bits
@@ -105,6 +108,9 @@ def fsqrt_test(x):
     sm >>= 2
     sm = get_mantissa(sm)
     #sm += 2
+
+    s, sm, se = normalise(s, sm, se, lowbits)
+
     print("our  sqrt", s, se, sm, hex(sm), bin(sm), "lowbits", lowbits,
                                                     "rem", hex(sr))
     if lowbits >= 2:
@@ -146,6 +152,9 @@ if __name__ == '__main__':
     x = Float32(0.123456)
     fsqrt_test(x)
 
+
+
+
 """
 
 Notes: