Introducing the Instruction Set Part 4 - Revision history

Mr z: Fixed some broken table markup. /* Using Shifts for Division by Powers of Two */

2011-07-04T07:38:03Z

Fixed some broken table markup. ‎Using Shifts for Division by Powers of Two

Mr z: Protected "Introducing the Instruction Set Part 4" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

2010-12-04T08:42:37Z

Protected "Introducing the Instruction Set Part 4" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

Mr z at 21:47, 21 November 2007

2007-11-21T21:47:41Z

Mr z: /* Using Shifts for Division by Powers of Two */

2007-11-04T00:04:31Z

‎Using Shifts for Division by Powers of Two

Mr z: /* Using Shifts for Division by Powers of Two */

2007-10-09T23:06:42Z

‎Using Shifts for Division by Powers of Two

Mr z: /* Shift and Rotate Diagrams */

2007-10-09T23:06:12Z

‎Shift and Rotate Diagrams

Mr z: /* Shift and Rotate Instructions */

2007-10-09T23:05:51Z

‎Shift and Rotate Instructions

Mr z at 22:58, 9 October 2007

2007-10-09T22:58:28Z

Mr z: /* Moving On */

2007-10-09T22:55:50Z

‎Moving On

Mr z: Introducing the Instruction Set Part 3 moved to Introducing the Instruction Set Part 4

2007-10-09T22:54:38Z

Introducing the Instruction Set Part 3 moved to Introducing the Instruction Set Part 4

@@ Line 150: / Line 150: @@
      SLR  Rx, 2
      INCR Rx
-     SLR  Rx, 1 </pre></CODE></TD></TR>
+     SLR  Rx, 1 </pre></CODE></TD>
 </TR>
 <TR><TD ALIGN=center>6</TD><TD ALIGN=center>64</TD>
@@ Line 186: / Line 186: @@
      SLR  Rx, 2
      INCR Rx
-     SLR  Rx, 1 </pre></CODE></TD></TR>
+     SLR  Rx, 1 </pre></CODE></TD>
-</TR></TR>
+</TR>
 <TR><TD ALIGN=center>8</TD><TD ALIGN=center>256</TD>
 <TD><CODE><pre>    SAR  Rx, 2

← Older revision		Revision as of 21:47, 21 November 2007
Line 1:		Line 1:
		+	[[Category: Programming]][[Category: Tutorial]]
		+
	This short tutorial examines the shift and rotate instructions. These are useful instructions, but somewhat more specialized than the rest of the instruction set. If you haven't read [[Introducing the Instruction Set Part 1\|Part 1]], [[Introducing the Instruction Set Part 2\|Part 2]] or [[Introducing the Instruction Set Part 3\|Part 3]] yet, you might consider doing so first.		This short tutorial examines the shift and rotate instructions. These are useful instructions, but somewhat more specialized than the rest of the instruction set. If you haven't read [[Introducing the Instruction Set Part 1\|Part 1]], [[Introducing the Instruction Set Part 2\|Part 2]] or [[Introducing the Instruction Set Part 3\|Part 3]] yet, you might consider doing so first.

@@ Line 94: / Line 94: @@
 Right shifts divide by powers of two, by default truncating the fractional portion.  This is the same as rounding towards negative.  With a minor tweak, the same code can round upwards. The following table shows example code sequences for various power-of-two divides on signed numbers and unsigned numbers.
 <TABLE BORDER CELLPADDING=5>
-<TR><TH>Number of positions<BR>shifted right</TH><TH>Power of 2<BR>divided by</TH><TH>Example Code Sequence for<BR>signed, rounding to negative</TH><TH>Example Code Sequence for<BR>signed, rounding to positive</TH><TH>Example Code Sequence for<BR>unsigned, rounding to negative</TH><TH>Example Code Sequence for<BR>unsigned, rounding to positive</TH></TR>
+<TR><TH>Number of positions<BR>shifted right</TH><TH>Power of 2<BR>divided by</TH><TH>Example Code Sequence for<BR>signed, rounding to negative</TH><TH>Example Code Sequence for<BR>signed, rounding to positive</TH><TH>Example Code Sequence for<BR>unsigned, rounding toward 0</TH><TH>Example Code Sequence for<BR>unsigned, rounding to positive</TH></TR>
 <TR><TD ALIGN=center>1</TD><TD ALIGN=center>2</TD>
 <TD><CODE><pre>    SAR  Rx, 1 </pre></CODE></TD>

@@ Line 203: / Line 203: @@
 </TR>
 </TABLE>
 == Combining Shifts and Rotates for Extended-Precision Shifts ==

@@ Line 24: / Line 24: @@
 Rotates are like shifts, except that they fill the vacated bits with bits from a status register.  By itself, this property has no particular mathematical meaning.  When rotates combine with shifts, though, they can perform extended-precision operations.
-== Shift and Rotate Diagrams ==
+== Shift and Rotate Diagram Summary ==
 The following diagrams illustrate the behavior of each of the 8 shift and rotate instructions.  Click on the links below for more detail.

← Older revision	Revision as of 08:42, 4 December 2010
(No difference)

@@ Line 3: / Line 3: @@
 = Shift and Rotate Instructions =
-The CP1610 offers a rich variety of shift and rotate instructions.  These are useful for bit manipulation and certain types of mathematics.  Shifting left by one position is equivalent to multiplying by 2.  Shifting right by one position is roughly equivalent to dividing by 2.  The shift instructions only operate on R0 through R3.  You  cannot use them with R4 through R7.  Overall, CP-1600 offers 8 separate shift instructions.  Each can shift by one or two positions.
+The CP1610 offers a rich variety of shift and rotate instructions.  Each can shift by one or two positions.  The shift instructions only operate on R0 through R3.  You cannot use them with R4 through R7.
 Click on a given mnemonic to see how it operates.
@@ Line 18: / Line 18: @@
 </TABLE>
-Logical shifts (SLL, SLR, SLLC) fill the newly-opened positions with zeros.  Arithmetic shifts (SAR, SARC) fill the newly opened positions with copies of bit 15.  Logical right shifts can be thought of as "unsigned divide by 2", whereas arithmetic right shifts can be thought of as "signed divide by 2, rounding toward negative."
+Shifts and rotates are useful for bit manipulation and certain types of mathematics, such as random number generation.  Logical shifts (SLL, SLR, SLLC) fill the newly-opened positions with zeros.  Arithmetic shifts (SAR, SARC) fill the newly opened positions with copies of bit 15.  Logical right shifts can be thought of as "unsigned divide by 2", whereas arithmetic right shifts can be thought of as "signed divide by 2, rounding toward negative."
 Rotates are like shifts, except that they fill the vacated bits with bits from a status register.  By itself, this property has no particular mathematical meaning.  When rotates combine with shifts, though, they can perform extended-precision operations.
-== Shift and Rotate Illustrations ==
+== Shift and Rotate Diagrams ==
 The following diagrams illustrate the behavior of each of the 8 shift and rotate instructions.  Click on the links below for more detail.

@@ Line 1: / Line 1: @@
-This short tutorial examines the shift instructions.  If you haven't read [[Introducing the Instruction Set Part 1|Part 1]] or [[Introducing the Instruction Set Part 2|Part 2]] yet, you might consider doing so first.
+This short tutorial examines the shift and rotate instructions.  These are useful instructions, but somewhat more specialized than the rest of the instruction set.  If you haven't read [[Introducing the Instruction Set Part 1|Part 1]], [[Introducing the Instruction Set Part 2|Part 2]] or [[Introducing the Instruction Set Part 3|Part 3]] yet, you might consider doing so first.
 = Shift and Rotate Instructions =
@@ Line 248: / Line 248: @@
 <BR/><BR/>
-= Moving On =
+= Wrapping Up =
-At this point, you may wish to continue with the remaining parts of this tutorial:
+At this point, you may wish to revisit the earlier parts of this tutorial:
 * [[Introducing the Instruction Set Part 1]]:  The CPU, Memory and Registers; Primary Instructions and Addressing Modes

@@ Line 254: / Line 254: @@
 * [[Introducing the Instruction Set Part 1]]:  The CPU, Memory and Registers; Primary Instructions and Addressing Modes
 * [[Introducing the Instruction Set Part 2]]:  Single Register and Implied Operand Instructions
-<!--* [[Introducing the Instruction Set Part 3]]:  Shift and Rotate Instructions-->
+* [[Introducing the Instruction Set Part 3]]:  Branches, Conditional Branches and Calls
-* [[Introducing the Instruction Set Part 4]]:  Branches, Conditional Branches and Calls
+<!--* [[Introducing the Instruction Set Part 4]]:  Shift and Rotate Instructions-->
 Or, you can return to the [[Programming Tutorials]] index.

← Older revision	Revision as of 22:54, 9 October 2007
(No difference)