fork download
copy 
  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <math.h>
  4.  
  5. // function for checking that assembly code is computing the correct result
  6. double quadraticRootC(double a, double b, double c)
  7. {
  8.     return (-b + sqrt(b * b - 4 * a * c)) / (2 * a);
  9. }
  10.  
  11. double quadraticRoot(double a, double b, double c)
  12. {
  13.     double root;
  14.  
  15.     asm(
  16.         "fldl       %1       # a                   \n"
  17.         "fadd       %%ST     # 2a                  \n"
  18.         "fldl       %1       # a 2a                \n"
  19.         "fldl       %3       # c a 2a              \n"
  20.         "fmulp      %%ST(1)  # ac 2a               \n"
  21.         "fadd       %%ST     # 2ac 2a              \n"
  22.         "fadd       %%ST     # 4ac 2a              \n"
  23.         "fldl       %2       # b 4ac 2a            \n"
  24.         "fldl       %2       # b b 4ac 2a          \n"
  25.         "fmulp      %%ST(1)  # b^2 4ac 2a          \n"
  26.         "fsubp      %%ST(1)  # b^2-4ac 2a          \n"
  27.         "fsqrt               # sqrt(b^2-4ac) 2a    \n"
  28.         "fldl       %2       # b sqrt(b^2-4ac) 2a  \n"
  29.         "fchs                # -b sqrt(b^2-4ac) 2a \n"
  30.         "faddp      %%ST(1)  # -b+sqrt(b^2-4ac) 2a \n"
  31.         "fdivp      %%ST(1)  # -b+sqrt(b^2-4ac)/2a \n"
  32.         :"=t"(root)
  33.         :"m"(a), "m"(b), "m"(c)
  34.         );
  35.     return(root);
  36. }
  37.  
  38. int main(int argc, char **argv)
  39. {
  40.     double  a, b, c;
  41.     double  root, rootC;
  42.  
  43.     a = 3.0;
  44.     b = -5.0;
  45.     c = 1.0;
  46.     root = quadraticRoot(a, b, c);
  47.     rootC = quadraticRootC(a, b, c);
  48.  
  49.     printf("quadraticRoot(%.3f, %.3f, %.3f) = %.3f, %.3f\n", a, b, c, root, rootC);
  50.  
  51.     return 0;
  52. }
  53.  
Success #stdin #stdout 0s 2008KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
quadraticRoot(3.000, -5.000, 1.000) = 1.434, 1.434
https://ideone.com/JeqM4t
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!