#!perl -w
# (C) 2003 XDA Developers  itsme@xs4all.nl
#
# $Header$
#
use strict;
use integer;
$|=1;
# todo: fix overflow handling:
#fxpdiv(0x0400, 0x100, 12); printf(" wanted=%08lx\n", flp(0x400/0x1000, 0x100/0x1000, 12));
#fxpdiv(0x4000, 0x001, 12); printf(" wanted=%08lx\n", flp(0x4000/0x1000, 1/0x1000, 12));
if (0) {
for (my $aa=-30000 ; $aa<30000 ; $aa+=1234) {
    for (my $bb=-30001 ; $bb<30000 ; $bb+=1234) {
        dotest($aa, $bb);
    }
}
}
for my $aa ( -32768..-32766, -2..2, 32765..32767) {
    for my $bb ( -32768..-32766, -2..2, 32765..32767) {
        dotest($aa, $bb);
    }
}

exit(0);

sub dotest {
    my ($aa, $bb)= @_;
    fxpdiv($aa, $bb, 12);
    printf("  wanted=%08lx\n", flp($aa, $bb, 12));
}

sub flp {
    my ($r0, $r1, $r2)= @_;
    if ($r1==0) {
        return $r0<0 ? MININT() : MAXINT();
    }
    if ($r0>MAXINT()) { $r0 -= FULLINT(); }
    if ($r1>MAXINT()) { $r1 -= FULLINT(); }
    if ($r0<MININT()) { $r0 += FULLINT(); }
    if ($r1<MININT()) { $r1 += FULLINT(); }

    my $val= ($r0/$r1)* 2**$r2;
    return MAXINT() if ($val>MAXINT());
    return MININT() if ($val<MININT());
    return $val;
}

sub inttofxp {
    my ($a)= @_;
    if ($a<0) {
        return scalar armsub(0, (-$a)<<12);
    }
    else {
        return ($a)<<12;
    }
}

sub MAXINT { return -1+(1<<15); }
sub MININT { return -(1<<15); }
sub FULLINT { return (1<<16); }

sub fxpdiv {
    my ($r0, $r1, $r2)= @_;
    printf("%08x / %08x %2d", $r0, $r1, $r2);
    my $r3= 0;
    my $r4= 0;
    if (armtst($r1)==0) {
        $r0= (armtst($r0)<0) ? MININT : MAXINT;
        printf("      == %08lx DIVBYZERO", $r0);
        return $r0;
    }
    elsif (armtst($r1)<0) {
        $r1= armsub(0, $r1);
        $r4= armxor($r4, 1);
    }
    if (armtst($r0)==0) {
        $r0= 0;
        printf("      == %08lx", $r0);
        return $r0;
    }
    elsif (armtst($r0)<0) {
        $r0= armsub(0, $r0);
        $r4= armxor($r4, 1);
    }

    while (armtst($r0)>=0) {
        $r0= armlsl($r0, 1);
        $r2= armsub($r2, 1);
    }

    while (armtst($r1)>=0) {
        $r1= armlsl($r1, 1);
        $r2= armadd($r2, 1);
    }

    my $r6= 0;
    my $r7= 0;

    printf(" [%2d]", $r2);

    # I can generate an overflow here already if $r2>MAXBITS
    if (armtst($r2)<0) {
        $r0= 0;
        printf(" == %08lx UNDERFLOW", $r0);
        return $r0;
    }
    if ($r2>=16) {
        $r0= $r4?MININT:MAXINT;
        printf(" == %08lx OVERFLOW1", $r0);
        return $r0;
    }
    my $c;
    do {
        if ((armcmp($r0, $r1) || armcmp($r6, $r7))>=0) {
            ($c, $r0)= armsub($r0, $r1);
            ($c, $r6)= armsub($r6, $r7, $c);
        }
        else {
            $c= 0;
        }

        ($c, $r3)= armadd($r3, $r3, $c);
        if ($c) {
            $r0= $r4?MININT:MAXINT;
            printf(" == %08lx OVERFLOW2", $r0);
            return $r0;
        }
        ($c, $r1)= armlsr($r1, 1);
        $r7= armrrx($r7, $c);

        $r2= armsub($r2, 1);
    } while(armtst($r2)>=0);

    if (armtst($r3)<0) {
        $r0= $r4?MININT:MAXINT;
        printf(" == %08lx OVERFLOW3", $r0);
        return $r0;
    }

    if ($r4) {
        $r0= armsub(0, $r3);
    }
    else {
        $r0= $r3;
    }
    printf(" == %08lx", $r0);
    return $r0;
}


sub checkuint {
    my ($r0)= @_;
    my $c;
    if ($r0>=FULLINT) {
        $c= 1;
        $r0 -= FULLINT;
    }
    elsif ($r0<0) {
        $c= 1;
        $r0 += FULLINT;
    }
    else {
        $c= 0;
    }
    return ($c, $r0);
}
sub checksint {
    my ($r0)= @_;
    my $c;
    if ($r0>MAXINT) {
        $c= 1;
        $r0 -= FULLINT;
    }
    elsif ($r0<MININT) {
        $c= 1;
        $r0 += FULLINT;
    }
    else {
        $c= 0;
    }
    return ($c, $r0);
}


sub armadd {
    my ($r0, $r1, $c)= @_;
    
    $c=0  if (!defined $c);

    return checkuint($r0+$r1+$c);
}
sub armcmp {
    my ($r0, $r1)= @_;

    return armtst(scalar armsub($r0, $r1));
}
sub armlsl {
    my ($r0, $r1)= @_;

    my $c= 0;
    while ($r1--) {
        $r0 *= 2;
        ($c, $r0)= checkuint($r0);
    }
    return ($c, $r0);
}
sub armlsr {
    my ($r0, $r1)= @_;

    if ($r0<0) {
        $r0 += FULLINT;
    }

    my $c= 0;
    while ($r1--) {
        $c= ($r0&1)? 1 : 0;
        $r0= ($r0-$c)/2;
    }
    return ($c, $r0);
}
sub armrrx {
    my ($r0, $c)= @_;

    if ($r0<0) {
        $r0 += FULLINT;
    }
    my $cnew= ($r0&1)? 1 : 0;
    $r0= ($r0-$cnew)/2;

    if ($c) {
        $r0 += FULLINT()/2;
    }

    if ($r0>MAXINT) {
        $r0 -= FULLINT;
    }

    return ($cnew, $r0);
}
sub armsub {
    my ($r0, $r1, $c)= @_;

    $c=1  if (!defined $c);

    ($c, $r0)= checkuint($r0-$r1+$c-1);

    return (1-$c, $r0);
}
sub armtst {
    my ($r0)= @_;

    if ($r0<0 || $r0>MAXINT) {
        return -1;
    }
    elsif ($r0==0) {
        return 0;
    }
    else {
        return 1;
    }
}
sub armxor {
    my ($r0, $r1)= @_;

    return ($r0 ^ $r1);
}