Perlito5::X64::Assembler - add push/pop

fglock · Mar 24, 2013 · 0e13f14 · 0e13f14
1 parent 61a5f3c
commit 0e13f14
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Showing 2 changed files with 50 additions and 5 deletions.
diff --git a/src5/lib/Perlito5/X64/Assembler.pm b/src5/lib/Perlito5/X64/Assembler.pm
@@ -9,6 +9,25 @@ sub new {
 }
 
 
+# Return the high bit of the register code as a 0 or 1.  Used often when constructing the REX prefix byte.
+sub high_bit {
+    my ($reg) = @_;
+    return $reg->{code} >> 3;
+}
+
+# Return the 3 low bits of the register code.  Used when encoding registers in modR/M, SIB, and opcode bytes.
+sub low_bits {
+    my ($reg) = @_;
+    return $reg->{code} & 0x7;
+}
+
+# emit REX if needed
+sub emit_optional_rex_32 {
+    my ($reg) = @_;
+    Perlito5::X64::Assembler::emit(0x41) if $reg->high_bit();
+}
+
+
 package Perlito5::X64::Assembler;
 
 my @buffer;
@@ -94,11 +113,33 @@ sub is_uint16 {
 
 #--- instructions
 
-sub nop {
+sub _nop {
     emit(0x90);
 }
 
-sub ret {
+sub _pop {
+    my ( $dst ) = @_;
+    if ( is_register($dst) ) {
+        $dst->emit_optional_rex_32();
+        emit(0x58 | $dst->low_bits());
+    }
+    else {
+        die "push: don't know what to do with $dst";
+    }
+}
+
+sub _push {
+    my ( $src ) = @_;
+    if ( is_register($src) ) {
+        $src->emit_optional_rex_32();
+        emit(0x50 | $src->low_bits());
+    }
+    else {
+        die "push: don't know what to do with $src";
+    }
+}
+
+sub _ret {
     my ( $imm16 ) = @_;
     if ( !$imm16 ) {
         emit(0xC3);
@@ -125,7 +166,7 @@ The Perlito5 x64 backend
     use Perlito5::X64::Assembler;
 
     package Perlito5::X64::Assembler;
-    ret();
+    _ret();
     say to_hex();   # C3
 
 =head1 References

diff --git a/t5-x64/01_sanity.t b/t5-x64/01_sanity.t
@@ -25,13 +25,17 @@ say "1..4";
         print "not " if $out;
         say "ok # !is_register";
 
-    ret();
+    _ret();
         $out = to_hex();
         print "not " if $out ne 'C3';
         say "ok # $out";
-    ret(10);
+    _ret(10);
         $out = to_hex();
         print "not " if $out ne 'C3 C2 0A 00';
         say "ok # $out";
+
+    _push( rax );
+    _push( r14 );
+    say "# " . to_hex();
 }