Update README.md

README.md

@@ -196,7 +196,7 @@
   ((fixed32)(((fa>>8)*(fb>>8))>>16))
   ~~~
      1. Same as above, the same fuction as fa*fb>>32, first multiply fa/2^8, fb/2^8, and divide the remaining 2^16
-- a. div
+- b. div
   - fx32_div
   ~~~
   (fixed32)( (((fixed64)(fa) << FX32_QNUM) /(fb))) 
@@ -212,3 +212,44 @@
   ((((fa)<<24)/(fb))<<8)
   ~~~
      1. same as above, it has the same fuction as (fa<<32)/fb. First, fa is multiplied by 2^24, divided by fb, and then the remaining 2^8 is multiplied.
+- c. sin
+  - sin table
+  ~~~
+  const fixed32 fx32_SinTable[92] =  
+    {     
+        0,1143,2287,3429,4571,5711,6850,7986,9120,10252,11380,12504,13625,14742,15854,16961,18064,19160,20251,21336,22414,23486,24550,25606,26655, 27696,28729,29752,
+        30767,31772,32768,33753,34728,35693,36647,37589,38521,39440,40347,41243,42125,42995,43852,44695,45525,46340,47142, 47929,48702,49460,50203,50931,51643,52339,
+        53019,53683,54331,54963,55577,56175,56755,57319,57864,58393,58903,59395,59870,60326,60763, 61183,61583,61965,62328,62672,62997,63302,63589,63856,64103,64331,
+        64540,64729,64898,65047,65176,65286,65376,65446,65496,65526,65536,65526
+    };
+  ~~~
+  - sin fuction 
+  ~~~
+  fixed32 fx32_sind(fixed32 fa)
+{
+    int sign = 1;   
+    fixed32 ret0, diff;
+    int idx; 
+    if ( fa < 0 ) 
+    {
+        sign = -1;
+        fa *= -1; 
+    }
+    fa = fa % FX32_360; 
+    if ( fa >= FX32_180 ) 
+    {
+        sign *= -1;
+        fa -= FX32_180;
+    }
+    if ( fa > FX32_90 ) 
+        fa = FX32_180 - fa;
+    idx = fa>>16; 
+    ret0 = fx32_SinTable[idx]; 
+    diff = fx32_SinTable[idx+1]-ret0;
+    return ( sign *( ret0 + ((diff*(fa&0xFFFF))>>16) )); 
+}
+    ~~~
+
+
+
+