;function quadratic

;finds solutions to the quadratic equation:

;a*x^2+b*x+c=0

;C prototype:

;int quadratic(doublea,doubleb,doublec,

;double*root1,double*root2)

;Parameters:

;a,b,c-coefficients of powers ofquadratic equation(seeabove)

;root1-pointer to double to store first root in

;root2-pointer to double to store second root in

;Returnvalue:

;returns1 if real roots found,else 0

%define a qword[ebp+8]

%define b qword[ebp+16]

%define c qword[ebp+24]

%define root1dword[ebp+32]

%define root2 dword[ebp+36]

%define disc qword[ebp-8]

%define one_over_2a qword[ebp-16]

segment.data

MinusFour dw -4

segment.text

global _quadratic

_quadratic:

push ebp

mov ebp,esp

sub esp,16 ;allocate 2 doubles(disc & one_over_2a)

push ebx;must save original ebx

fild word [MinusFour] ; stack -4

fld a;stack:a,-4

fld c;stack:c,a,-4

fmulp st1;stack:a*c,-4

fmulp st1;stack:-4*a*c

fld b

fld b;stack:b,b,-4*a*c

fmulp st1;stack:b*b,-4*a*c

faddp st1;stack:b*b-4*a*c

ftst;testwith0

fstsw ax

sahf

jb no_real_solutions;if disc<0,no real solutions

fsqrt;stack:sqrt(b*b-4*a*c)

fstp disc;store and pop stack

fld1;stack:1.0

fld a;stack:a,1.0

fscale;stack:a*2^(1.0)=2*a,1

fdivp st1;stack:1/(2*a)

fst one_over_2a;stack:1/(2*a)

fld b;stack:b,1/(2*a)

fld disc;stack:disc,b,1/(2*a)

fsubrp st1;stack:disc-b,1/(2*a)

fmulp st1;stack:(-b+disc)/(2*a)

mov ebx,root1

fst p qword[ebx];store in*root1

fldb;stack:b

fld disc;stack:disc,b

fchs;stack:-disc,b

fsubrp st1;stack:-disc-b

fmul one_over_2a;stack:(-b-disc)/(2*a

mov ebx,root2

fstp qword[ebx];store in *root2

mov eax,1;return value is 1

jmp short quit

no_real_solutions:

mov eax,0;return value is 0

quit:

pop ebx

mov esp,ebp

pop ebp

ret