Update README.md

testing/README.md

@@ -30,3 +30,33 @@
       ~~~
       - to add two fixed point numbers there is no need to conversion of data type
       - just add two fixed point numbers and return result
+    - b. sub
+      ~~~
+      #define fx_sub(a, b) ((a)-(b))
+      ~~~
+      - to sub one fixed point number from another fixed point number there is no need to conversion of data type.
+      - just operate function without conversion of data type and return result
+    - c. mul
+      ~~~
+      #define fx_mul(a, b) double_to_fx(fx_to_double (a) * fx_to_double (b))
+      ~~~
+      - to mul two fixed pouint number shoul do type conversion
+      - first convert two fixed point number to double type and do mul operation
+      - second result calculated from first step should be converted to fixed point number(type conversion)
+    - d. div
+      ~~~
+      #define fx_div(a, b) double_to_fx(fx_to_double (a) / fx_to_double (b))
+      ~~~
+      - to div two fixed pouint number shoul do type conversion
+      - first convert two fixed point number to double type and do div operation
+      - second result calculated from first step should be converted to fixed point number(type conversion)
+    - e. fixed -> double
+      ~~~
+      #define fx_to_double(a) (a/P2_2to32)
+      ~~~
+      - to convert fixed point to double should divide fixed point number by 2^32(s31(32)=>decimal part bits)
+    - f. double -> fixed
+      ~~~
+      #define double_to_fx(a) (long long)(a*P2_2to32)
+      ~~~
+      - to convert double to fixed point should multiply double number and 2^32(s31(32)=>decimal part bits)
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