Changes from Version 1 of SplittingUbyteWithAsmExample

Author:

jcc7 (IP: 68.97.93.38)

Timestamp:

11/14/05 03:40:05 (18 years ago)

Comment:

--

SplittingUbyteWithAsmExample

@@ +1 @@
+= Asm code for splitting ubyte into low and high nibbles =
+
+''Part of'' TutorialIntermediate
+
+== Description ==
+
+Demonstrates using asm code with local variables
+
+== Example ==
+
+{{{
+#!d
+/*
+ *  Copyright (C) 2004 by Digital Mars, www.digitalmars.com
+ *  Written by Lynn Allan
+ *  This software is provided 'as-is' by a rusty asm-486 programmer.
+ *  Released to public domain.
+ *
+ * Compile with: dmd test.d (uses dmd ver 0.102)
+ */
+
+import std.stdio;
+
+void main ()
+{
+  ubyte x = 0x12;
+  ubyte y = 0x9a;
+  ubyte xLoNibble = (x & 0x0F);
+  ubyte xHiNibble = (x >> 4);
+  ubyte yLoNibble = (y & 0x0F);
+  ubyte yHiNibble = (y >> 4);
+  writefln("x: ", x, "  xLoNibble: ", xLoNibble, "  xHiNibble: ", xHiNibble);
+  writefln("y: ", y, "  yLoNibble: ", yLoNibble, "  yHiNibble: ", yHiNibble);
+
+  asm
+  {
+    movzx  BX,x;
+    mov    AX,BX;
+    and    BX,15;
+    mov    xLoNibble,BL;
+    shr    AX,4;
+    mov    xHiNibble,AL;
+
+    movzx  BX,y;
+    mov    AX,BX;
+    and    BX,15;
+    mov    yLoNibble,BL;
+    shr    AX,4;
+    mov    yHiNibble,AL;
+  }
+  assert(xLoNibble == 2);
+  assert(xHiNibble == 1);
+  assert(yLoNibble == 10);
+  assert(yHiNibble == 9);
+  writefln("x: ", x, "  xLoNibble: ", xLoNibble, "  xHiNibble: ", xHiNibble);
+  writefln("y: ", y, "  yLoNibble: ", yLoNibble, "  yHiNibble: ", yHiNibble);
+}
+}}}
+
+== Source ==
+
+|| Link || http://www.dsource.org/tutorials/index.php?show_example=127 ||
+|| Posted by || Anonymous ||
+|| Date/Time || Mon Oct 4, 2004 10:47 am ||