AN 977: Nios® V Processor Custom Instruction

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ID 773194
Date 4/14/2023
Public
Document Table of Contents
Document Table of Contents x
1. Nios® V Processor Custom Instruction Overview 2. Custom Instruction Hardware Interface 3. Custom Instruction Software Interface 4. Designing with Intel® Quartus® Prime and Platform Designer 5. Document Revision History for AN 977: Nios® V Processor Custom Instruction
1. Nios® V Processor Custom Instruction Overview x
1.1. Implementing Custom Instruction 1.2. Implementing Custom Instruction Logic Block 1.3. Implementing Custom Instruction Software
2. Custom Instruction Hardware Interface x
2.1. Custom Instruction Types 2.2. Multicycle Custom Instructions 2.3. Extended Custom Instruction 2.4. External Interface Custom Instructions
2.2. Multicycle Custom Instructions x
2.2.1. Multicycle Custom Instruction Ports 2.2.2. Multicycle Custom Instruction Timing 2.2.3. Implementing Combinational Custom Instruction
2.3. Extended Custom Instruction x
2.3.1. Extended Custom Instruction Timing
3. Custom Instruction Software Interface x
3.1. Custom Instruction Software C Macro 3.2. Custom Instruction Assembly Language Interface 3.3. Custom Instruction Word Format
3.2. Custom Instruction Assembly Language Interface x
3.2.1. Custom Instruction Assembly Language Syntax
3.3. Custom Instruction Word Format x
3.3.1. Selector and Extension Indexes 3.3.2. ALU Switch 3.3.3. User-defined Immediate
4. Designing with Intel® Quartus® Prime and Platform Designer x
4.1. Interface Signals 4.2. Custom Instruction Manager 4.3. Custom Instruction Subordinate
4.1. Interface Signals x
4.1.1. alu_result port 4.1.2. ctrl port
4.2. Custom Instruction Manager x
4.2.1. Hardware Interfaces Table 4.2.2. Software C-Macro Table
4.3. Custom Instruction Subordinate x
4.3.1. Writing the Custom Instruction HDL File 4.3.2. Opening the Component Editor 4.3.3. Specifying the Custom Instruction Component Type 4.3.4. Displaying the Custom Instruction Block Symbol 4.3.5. Adding the Custom Instruction HDL File 4.3.6. Configuring the Custom Instruction Parameter Type 4.3.7. Setting Up the Custom Instruction Interfaces 4.3.8. Saving and Adding the Custom Instruction 4.3.9. Generating and Compiling the Processor System
1. Nios® V Processor Custom Instruction Overview
2. Custom Instruction Hardware Interface
3. Custom Instruction Software Interface
4. Designing with Intel® Quartus® Prime and Platform Designer
5. Document Revision History for AN 977: Nios® V Processor Custom Instruction

3.1. Custom Instruction Software C Macro

The following examples illustrate how the Nios® V processor custom instruction software interface fits into the software code.

The example below shows a portion of the system.h header file that defines a macro for a custom instruction. The macros defined by the Board Support Package Editor use C integer types only.

Software C Macros with assigned funct3 and funct7 fields 

#define CUSTOM_OPERATION(VAL_1, VAL_2) ({ \ 
 int output; \ 
 asm volatile (".insn r  0x0B, 0x1, 0x0, %[out], %[input1], %[input2]" \ 
: [out] "=r" (output) \ 
: [input1] "r" (VAL_1), [input2] "r" (VAL_2)); \ 
output;  \ 
})
Note: The example above assigns funct3 as 0x1 and funct7 as 0x0.

The example below shows an application code that uses the custom instruction and includes the system.h file. This example enables the application software to use the custom instruction macro definition. You are required to apply uint32_t variable type, along with inttypes.h header.

Software C Macros that includes system.h 

#include "system.h"
#include <inttypes.h>
int main (void)

{
uint32_t val_1 = 0x12345678;      //max 32-bit
uint32_t val_2 = 0x98765432;      //max 32-bit
uint32_t result;
	
	result = CUSTOM_OPERATION_1(val_1, val_2);
	return 0;
}
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