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POx86 assembly routine stuck for no reason
 

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  1. POx86 assembly routine stuck for no reason
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    <p>I have below this program and for some reason that I can't find my assembly routine gets stuck.</p> <p>I already checked <code>SP</code> and that the code returns to the right place where it should and that the stack is always as it should.</p> <p>There is only one thing I've done so that the routine didn't get stuck was to change the jump to <code>JNL</code>, with any other jump it gets stuck.</p> <p>This is my code in C and assembly. In the end there is a C code that shows what the assembly routine should do.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;math.h&gt; #include &lt;conio.h&gt; extern void two_point (double (*f1)(double, double), double (*f2)(double, double), double x, double y, double *ptr1, double *ptr2); extern void fixed2 (double (*f1)(double, double), double (*f2)(double, double), double x0, double y0, double *ptr1, double *ptr2, double eps); double f1 (double x, double y); double f2 (double x, double y); int main() { double x, y; fixed2 (f1, f2, 1.4, 1.4, &amp;x, &amp;y, 0.001); printf ("x= %lf, y= %lf\n", x, y); return 0; } double f1 (double x, double y) { return sin (x+y); } double f2 (double x, double y) { return cos (x+y); } </code></pre> <p>ASM CODE:</p> <pre><code>;HW4a.asm .MODEL SMALL .DATA x0 DQ ? x1 DQ ? y0 DQ ? y1 DQ ? x2 DQ ? y2 DQ ? element DW 16;double*2 .CODE .386 .387 ;two_point (double (*f1)(double, double), double (*f2)(double, double), double x, double y, double *ptr1, double *ptr2) ;f1=BP+4, f2=BP+6, x=BP+8, y=BP+16, ptr1=BP+24, ptr2=BP+26 _two_point PROC NEAR PUSH BP MOV BP,SP PUSH SI PUSH DI MOV SI,WORD PTR[BP+24] MOV DI,WORD PTR[BP+26] FLD QWORD PTR [BP+16];ST0=Y FSTP y2 FLD QWORD PTR [BP+8];ST0=X FSTP x2 PUSH DWORD PTR y2+4 PUSH DWORD PTR y2 PUSH DWORD PTR x2+4 PUSH DWORD PTR x2 ;f1: CALL [BP+4];CALL F1 FSTP QWORD PTR [SI];SI GET RETURNED VALUE FROM F1 MOV [BP+24],SI;PTR1=F1(X,Y) ;f2: CALL [BP+6];CALL F2 FSTP QWORD PTR [DI];DI GET RETURNED VALUE FROM F2 MOV [BP+26],DI;PTR2=F2(X,Y) ;end: ADD SP,element POP DI POP SI POP BP RET _two_point ENDP ;fixed2 (double (*f1)(double, double), double (*f2)(double, double), double x0, double y0, double *ptr1, double *ptr2, double eps) ;f1=BP+4, f2=BP+6, x0=BP+8, y0=BP+16, ptr1=BP+24, ptr2=BP+26, eps=BP+28 PUBLIC _fixed2 _fixed2 PROC NEAR PUSH BP MOV BP,SP ;pre loop: PUSH SI PUSH DI MOV SI,WORD PTR[BP+24];SI=&amp;ptr1 MOV DI,WORD PTR[BP+26];DI=&amp;ptr2 FLD QWORD PTR [BP+16];ST0=Y FST y0 FSTP y1 FLD QWORD PTR [BP+8];ST0=X FST x0 FSTP x1 LOOPER: FLD y1 FST y0;y0=y1 FSTP QWORD PTR [DI];SI=&amp;y1 PUSH WORD PTR DI;push &amp;y1 FLD x1 FST x0;x0=x1 FSTP QWORD PTR [SI];SI=&amp;x1 PUSH WORD PTR SI;push &amp;x1 PUSH DWORD PTR y0+4 PUSH DWORD PTR y0 PUSH DWORD PTR x0+4 PUSH DWORD PTR x0 PUSH WORD PTR [BP+6];push f2 PUSH WORD PTR [BP+4];push f1 CALL _two_point MOV DI,WORD PTR [BP-6];DI=&amp;y0 MOV SI,WORD PTR [BP-8];SI=&amp;x0 ADD SP,8;sizeof(f1+f2)+sizeof(*ptr1+*ptr2) ADD SP,element FLD QWORD PTR [SI];load x1 FST x1 FLD x0 FSUB FABS;|x1-x0| FLD QWORD PTR [DI];load y1 FST y1 FLD y0 FSUB FABS;|y1-y0| FADD;ST[0]=|y1-y0|+|x1-x0| FLD QWORD PTR [BP+28];ST[0]=eps FCOMPP;ST[0]-ST[1] FSTSW AX SAHF JBE LOOPER;while ((fabs(x1-x0) + fabs(y1-y0))&gt;=eps) ;end: FLD x1 FSTP QWORD PTR [SI] MOV WORD PTR [BP+24],SI;update *ptr1=x1 FLD y1 FSTP QWORD PTR [DI] MOV WORD PTR [BP+26],DI;update *ptr2=y1 POP DI POP SI POP BP RET _fixed2 ENDP END </code></pre> <p>and this is what the ASM SHOULD DO:</p> <pre><code>void fixed2 (double (*f1)(double, double), double (*f2)(double, double), double x0, double y0, double *ptr1, double *ptr2, double eps) { double x1= x0, y1= y0; do { x0= x1; y0= y1; two_point (f1, f2, x0, y0, &amp;x1, &amp;y1); } while ((fabs(x1-x0) + fabs(y1-y0))&gt;=eps); *ptr1 = x1; *ptr2 = y1; } </code></pre> <p>F1 and F2:</p> <pre><code>double f1 (double x, double y) { return sin (x+y); } double f2 (double x, double y) { return cos (x+y); } </code></pre>
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    1. USshimon
    1. USshimon
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      1. POx86 assembly routine stuck for no reason
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      1. VTDownMod
    1. COAsking others to spot the errors in your code isn't productive. You should step through your code in a debugger; then you will discover where precisely it is "stuck".
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      1. POx86 assembly routine stuck for no reason
      1. USOliver Charlesworth
    2. COtrust me, i lived in the debugger for the last 3 days, still cant find :( as you can see i said that i checked SP which means i had to see it in the debugger
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      1. POx86 assembly routine stuck for no reason
      1. USshimon
    3. COWell, it's definitely not stuck for no reason; unfortunately you'll need to debug to find out what that reason is.
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      1. POx86 assembly routine stuck for no reason
      1. USSaggio
 

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