Official Manual for PicoBlaze Instruction Set - UG129

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Chapter 3: PicoBlaze Instruction Set

ADD sX,01 ; increment register sX

SUB sX,01 ; decrement register sX

Figure 3-10:Incrementing and Decrementing a Register

If incrementing or decrementing a multi-register value—i.e., a 16-bit value—perform the operation using multiple instructions. Incrementing or decrementing a multi-byte value requires using the add or subtract instructions with carry, as shown in Figure 3-11.

inc_16:

;increment low byte ADD lo_byte,01

;increment high byte only if CARRY bit set when incrementing low byte ADDCY hi_byte,00

Figure 3-11:Incrementing a 16-bit Value

Negate

The PicoBlaze microcontroller does not have a dedicated instruction to negate a register value, taking the two’s complement. However, the instructions in Figure 3-12provide the equivalent operation.

Negate:

;invert all bits in the register performing a one’s complement XOR sX,FF

;add one to sX

ADD sX,01

RETURN

Figure 3-12:Destructive Negate (2’s Complement) Function Overwrites Original

Value

Another possible implementation that does not overwrite the value appears in Figure 3-13.

Negate:

NAMEREG sY, value

NAMEREG sX, complement

;Clear ‘complement’ to zero LOAD complement, 00

;subtract value from 0 to create two’s complement SUB complement, value

RETURN

Figure 3-13:Non-destructive Negate Function Preserves Original Value

Multiplication

The PicoBlaze microcontroller core does not have a dedicated hardware multiplier. However, the PicoBlaze microcontroller performs multiplication using the available arithmetic and shift instructions. Figure 3-14demonstrates an 8-bit by 8-bit multiply routine that produces a 16-bit multiplier product in 50 to 57 instruction cycles, or 100 to 114 clock cycles. By contrast, the 8051 microcontroller performs the same multiplication in eight instruction cycles or 96 clock cycles on a the standard 12-cycle 8051.

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		UG129 (v1.1.2) June 24, 2008

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Xilinx UG129 manual Multiplication, 10Incrementing and Decrementing a Register

Contents

PicoBlaze 8-bit Embedded Microcontroller User Guide UG129 v1.1.2 June 24 Revision History Version Revision Limited Warranty and Disclaimer LimitationsLimitation of Liability Technical Support Limitations Acknowledgments Preface Acknowledgments Guide Contents About This Guide Preface About This Guide Table of Contents Interrupts Performance Appendix C PicoBlaze Instruction Set and Event Reference PicoBlaze Microcontroller Features Introduction PicoBlaze Microcontroller Functional Blocks General-Purpose RegistersInstruction Program Store Introduction Arithmetic Logic Unit ALU FlagsByte Scratchpad RAM Input/Output Reset Program Counter PCProgram Flow Control CALL/RETURN Stack Why Use a Microcontroller within an FPGA? Why the PicoBlaze Microcontroller?Why the PicoBlaze Microcontroller? Strengths Weaknesses PicoBlaze Interface Signal Descriptions PicoBlaze Interface SignalsSignal Direction Description Readstrobe PicoBlaze Instruction Set 1PicoBlaze Instruction Set alphabetical listing Enable Interrupt Returni Disable Address Spaces Instruction 1Kx18 Direct Logic Instructions Processing DataPicoBlaze Instruction Set 2Complementing a Register Value 3Inverting an Individual Bit Location 616-Setting a Bit Location Arithmetic Instructions SUB and Subcy Subtract Instructions Multiplication 10Incrementing and Decrementing a Register 148-bit by 8-bit Multiply Routine Produces a 16-bit Product 168-bit by 8-bit Multiply Routine Using Hardware Multiplier Division No Operation NOP 18Loading a Register with Itself Acts as a NOP Instruction Setting and Clearing Carry Flag Test and Compare 22The Test Instruction Affects the Zero Flag 25Generate Parity for a Register Using the Test Instruction Shift and Rotate Instructions SRX 5PicoBlaze Rotate Instructions Rotate Left Rotate Right Moving Data Program Flow Control Program Flow Control 6Instruction Conditional Execution Description CALL/RETURN Program Flow Control UG129 v1.1.2 June 24 Interrupts 1Simple Interrupt Logic Example Interrupt Flow 2Example Interrupt Flow 3Interrupt Timing Diagram Example Interrupt Flow Interrupts Scratchpad RAM Address ModesDirect Addressing Indirect Addressing Implementing a Look-Up Table Scratchpad RAM Fifo Operations Stack OperationsStack Operations Scratchpad RAM Input and Output Ports Portid Port Input Operations 1INPUT Operation and Fpga Interface Logic Input Operations PORTID70INPORT70 Register s0 Readstrobe Interaction with FIFOs Applications with Few Input SourcesInput and Output Ports Output Operations Output Operations Simple Output Structure for Few Output Destinations Fpga Register 8Use Constant Directives to Declare Output Port Addresses Pipelining for Maximum Performance 9Pipelining the Portid Decoding Improves Performance Pipelining for Maximum Performance Repartitioning the Design for Maximum Performance Effective Pipelining Improves Read Performance Instruction Storage Configurations Standard Configuration Single 1Kx18 Block RAM Instruction Storage Configurations Two PicoBlaze Microcontrollers Share a 1Kx18 Code Image 6Using Distributed ROM for Instruction Memory Distributed ROM Instead of Block RAM Instruction Storage Configurations Performance Input Clock FrequencyPredicting Executing Performance Frequency Performance PicoBlaze Development Tools Assembler Input and Output Files Assembly ErrorsPicoBlaze Development Tools Configuring pBlazIDE for the PicoBlaze Microcontroller Mediatronix pBlazIDE Importing KCPSM3 Code into pBlazIDE 4Example of How Kcpsm Source Code Converts to pBlazIDE Code Differences Between the KCPSM3 Assembler and pBlazIDE DirectivesDifferences Between the KCPSM3 Assembler and pBlazIDE Function KCPSM3 Directive PBlazIDE Directive PicoBlaze Development Tools Vhdl Design Flow Using the PicoBlaze Microcontroller in an Fpga DesignKCPSM3 Module Connecting the Program ROM Using the PicoBlaze Microcontroller in an Fpga Design Black Box Instantiation of KCPSM3 using KCPSM3.ngc Generating the Program ROM using progrom.coeGenerating an ESC Schematic Symbol Black Box Instantiation of KCPSM3 using KCPSM3.ngc Using the PicoBlaze Microcontroller in an Fpga Design Locating Code at a Specific Address Assembler DirectivesNaming or Aliasing Registers Defining Constants Naming the Program ROM Output FileDefining I/O Ports pBlazIDE PBlazIDE Output Ports Input PortsDefining I/O Ports pBlazIDE Input/Output Ports 5Example of pBlazIDE Dsout Directive Custom Instruction Op-Codes Custom Instruction Op-Codes Assembler Directives Simulating PicoBlaze Code Instruction Set Simulation with pBlazIDE Simulator Control Buttons Instruction Set Simulation with pBlazIDE2pBlazIDE Simulator Control Buttons Function Assemble Edit Run Step OverRun to Cursor Pause Turbocharging Simulation using FPGAs Turbocharging Simulation using FPGAs Simulating PicoBlaze Code Related Materials and References Chapter Related Materials and References Example Program Templates KCPSM3 Syntax PBlazIDE Syntax Appendix Example Program Templates PicoBlaze Instruction Set and Event Reference ADD sX, Operand -Add Operand to Register sX Addcy sX, Operand -Add Operand to Register sX with Carry Appendix PicoBlaze Instruction Set and Event Reference SX, Operand Logical Bitwise and Register sX with Operand SX, Operand Logical Bitwise and Register sX with Operand Examples Condition Table C-1CALL Instruction Conditions Description Compare sX, Operand Compare Operand with Register sX Figure C-4COMPARE Operation Enable Interrupt Enable External Interrupt Input Disable Interrupt Disable External Interrupt InputDisable Interrupt Disable External Interrupt Input Figure C-5FETCH Operation KCPSM3 Instruction PBlazIDE Instruction Portid Å Operand SX Å Inport PC Å PC + Interrupt Event, When Enabled Table C-2JUMP Instruction Conditions Description Load sX, Operand Load Register sX with Operand Or sX, Operand Logical Bitwise or Register sX with Operand Or sX, Operand Logical Bitwise or Register sX with Operand Figure C-7OUTPUT Operation and Fpga Interface Logic Reset Event Reset EventTable C-3PicoBlaze Reset Values Resource Reset Event Effect Table C-4RETURN Instruction Conditions Description PBlazIDE Equivalent RET, RET C, RET NC, RET Z, RET NZ RL sX Rotate Left Register sX RR sX Rotate Right Register sXTable C-5Rotate Left RL Operation Table C-6Rotate Right RR Operation SL 0 1 X a sX Shift Left Register sX SL 0 1 X a sX Shift Left Register sXTable C-7Shift Left Operations SR 0 1 X a sX Shift Right Register sX Shift Right with ‘ 0’ fill Figure C-8STORE Operation SUB sX, Operand -Subtract Operand from Register sX Store sX, sY Figure C-10SUBCY Instruction Registers sX Flags CARRY, Zero PBlazIDE Equivalent Subc Figure C-11ZERO Flag Logic for Test Instruction PicoBlaze 8-bit Embedded Microcontroller 117 XOR sX, Operand Logical Bitwise XOR Register sX with Operand Instruction Codes Table D-1PicoBlaze Instruction Codes Jump Z PicoBlaze 8-bit Embedded Microcontroller 121 Appendix Instruction Codes Registers Register and Scratchpad RAM Planning WorksheetsReg Description Appendix Register and Scratchpad RAM Planning Worksheets Scratchpad RAMLoc Description