format ELF include '../proc32.inc' section '.text' executable public acos_ as "acos" acos_: ; acos(x) = atan(sqrt((1-x*x)/(x*x))) fld qword[esp+4] fld st0 ;Duplicate X on tos. fmul st0, st1 ;Compute X**2. fld st0 ;Duplicate X**2 on tos. fld1 ;Compute 1-X**2. fsub st0, st1 fdiv st0, st1 ;Compute (1-x**2)/X**2. fsqrt ;Compute sqrt((1-X**2)/X**2). fld1 ;To compute full arctangent. fpatan ;Compute atan of the above. ret