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Computer Architecture Lab/Winter2006/HoeftPirkWeirHuang/InstructionSetII/More

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VHDL-Source for NORISK-Chip (hardware-programmer, CPU)

Features edit

  • 32-bit Harvard processor architecture
  • Dual-ported Instruction Memory
  • Word addresses
  • Memory Mapped IO
  • On Chip-Memory programmer
  • 16 general purpose registers
  • 16-bit instructions
  • Instruction preprocessing
  • 3-stage piplining
  • 1 cycle relative conditional branches
  • 1 cycle absolute jumps
 
Block Diagram of the NORISK Processor

Instruction Set edit

Three Operands edit

The 8-bit immediate values are unsigned, 11-bit branch values are signed.

3 Operands
Name OpCode Operands Note Decoding
ADD 0000 ddddrrrraaaa D = R + A; 00000
ADC 0001 ddddrrrraaaa D = R + A + C 00001
SUB 0010 ddddrrrraaaa D = R - A 00010
SBC 0011 ddddrrrraaaa D = R - A - c 00011
AND 0100 ddddrrrraaaa D = R and A 00100
OR 0101 ddddrrrraaaa D = R or A 00101
CMPI 0110 rrrriiiiiiii R - I => flags 10000
XOR 0111 ddddrrrraaaa D = R xor A 00110
LDB0 1000 rrrriiiiiiii R(31~8) = 0, R(7~0) = I 01000
LDB1 1001 rrrriiiiiiii R(31~16) = 0, R(15~8) = I 01001
LDB2 1010 rrrriiiiiiii R(31~24) = 0, R(23~16) = I 01010
LDB3 1011 rrrriiiiiiii R(31~24) = I 01011
RJMP 11000 iiiiiiiiiii PC = PC + I 100xx (not 10000)
RCALL 11001 iiiiiiiiiii R15 = PC; PC = PC + I 100xx (not 10000)
BRNE 11010 iiiiiiiiiii if(!zero) PC = PC + I 100xx (not 10000)
BREQ 11011 iiiiiiiiiii if(zero) PC = PC + I 100xx (not 10000)
BRCC 11100 iiiiiiiiiii if(!carry) PC = PC + I 100xx (not 10000)
BRCS 11011 iiiiiiiiiii if(carry) PC = PC + I 100xx (not 10000)

Two Operands edit

All 4-bit immediate values are unsigned.

2 Operands (2 instructions available)
Name OpCode Operands Note Decoding
ADDI 11110000 rrrriiii R = R + I 00000
ADCI 11110001 rrrriiii R = R + I + C 00001
SUBI 11110010 rrrriiii R = R - I 00010
SBCI 11110011 rrrriiii R = R - I - C 00011
LSL 11110100 rrrrssss R <<= S 01110
ASL 11110101 rrrrssss R >>>= S 01111
CMP 11110110 rrrraaaa R = A => zero flag 10000
11110111
ROL 11111000 rrrrssss 01100
ROR 11111001 rrrrssss 01101
ST 11111010 ddddaaaa [A] = D 100xx (not 10000)
LD 11111011 ddddaaaa D = [A] 11xxx
LSLI 11111100 rrrriiii R <<= I 01110
ASRI 11111101 rrrriiii R >>>= I 01111
MOV 11111110 ddddssss D = S 10101
11111111

One Operand edit

1 Operand (9 instructions available)
Name OpCode Operand Note Decoding
JMP 111111110000 rrrr PC = R
CALL 111111110001 rrrr PC => [SP], SP--, PC = R
PUSH 111111110010 rrrr R => [SP], SP--
POP 111111110011 rrrr SP++, [SP] => R
NEG 111111110100 rrrr R = -R 10101
COM 111111110101 rrrr R = not R 00111
PAR 111111110110 rrrr 1s in R
111111110111

Non Operand edit

0 Operand (3 instructions available)
Name OpCode Note Decoding
RET 1111111111110000 SP++, [SP] => PC
RETI 1111111111110001
CLI 1111111111110010 Interrupt flag = 0
SEI 1111111111110011 Interrupt flag = 1
SKIPCC 1111111111110100
SKIPCS 1111111111110101
SKIPNE 1111111111110110
SKIPEQ 1111111111110111
SKIPNO 1111111111111000
SKIPOV 1111111111111001
SKIPNOTNEG 1111111111111010
SKIPNEG 1111111111111011
1111111111111100
1111111111111101
1111111111111110
NOP 1111111111111111 100xx (not 10000)

Pipelining edit

The NORISK Processor implements three-stage pipelining:

  • Instruction fetching and simple branch logic
  • Decoding
  • Execution and Memory Access

Macro Assembler edit

The macro assembler was written using flex and yacc. The goal was to produce an intuitive assembler. It allows C-style usage of assembly operations.

C/C++, Flex, Yacc-Sources for assembler and instruction set simulator. Assembler-Sources for example assembly programs.

Data memory initialization edit

  • Zero initialized 32bit words:

word identifier[size]

  • User initialized 32bit words: (size determined by assembler)

word identifier[]=word1,word2,word3,...

  • User initialized 32bit words: (size determined by programmer)

word identifier[size]=word1,word2,word3,...

  • String:

word identifier[]="string"

  • String: (size determined by programmer)

word identifier[size]="string"

Data transfer edit

  • Register-Register:

rXX = rYY

  • Register-Memory and Memory-Register

rXX = rYY[disp]
rXX[disp] = rYY
Displacement values above zero are not possible with the current NORISK instruction-set.

  • Register-Immediate

rXX = immediate
Immediate values can be numeric (0x for hexadecimal), labels or storage variables.

Arithmetic Operations edit

  • Possible operations are &,|,^,<<,>>, <R< (rotate left), >R> (rotate right), >A> (arithmetic shift right)
  • Syntax 1: rXX = rYY op rZZ
  • Syntax 2: rXX op=rZZ

rXX is source and destination

  • For some operations (depending on the instruction set) immediate values instead of rZZ are possible.

Control flow edit

  • Labels: identifier followed by :
  • Branch: goto label
  • Conditional branch: goto label if condition
  • Flag conditions: carry, !carry, zero, !zero
  • Compare conditions: rXX {< or <= or > or >= or == or !=} {rYY or immediate}

This type of conditions produce a CMP operation before the branch.

  • Relative call: rcall label. Saves next PC in register 15 and performs a relative jump.
  • Return: return

Example program: bubble-sort edit 

word test[]={20,20,21,19,15,1,10,12,6,7,3,100, 99,98,97}

r5 = sizeof(test)
r5 = r5+r0  ; calculate end

outer_loop:
r1 = test ; memory address of 1st operand
r2 = test ; memory address of 2nd operand
r2 += 1
r6 = 0  ; flag if sort is completed

inner_loop:
r3 = r1[0] ; load operands
r4 = r2[0]

goto next if r3 <= r4 ; decide whether it is necessary to swap them
r2[0] = r3 ; swap elements
r1[0] = r4
r6 += 1    ; set not-done flag

next:
r1 += 1
r2 += 1 ; next index
goto inner_loop if r2 < r5 ; repeat if end not reached
goto outer_loop if r6 != 0 ; repeat if sort not finished

r0 = 0x80000000 ; IO-address for leds
r1 = 0xF
r0[0] = r1 ; illuminate four leds

infinite:
goto infinite ; loop forever

Call Parameters edit

ass prgm_file bin_out [bin_data_out]

  • prgm_file is the source code file
  • bin_out is the binary code output
  • bin_data_out is the binary data output. If this parameter is omitted, a default value (based on the bin_out parameter) is used.

Instruction Set Simulator edit

Call Parameters edit

iss prgmmem datamem [datamem_out]

  • prgmmem is the filename of assembly program code output
  • datamem is the filename of assembly data output
  • datamem_out is optional. If specified the contents of the data memory after quit are written to that file.

During Operation edit

  • Enter executes next instruction
  • Sometimes IO input is requested (prompt: [IO@ address]:) the value specified is returned for this load operation. 0x for hexadecimal is allowed.
  • q stops execution and writes data file

On chip-memory programmer edit

Visual C++ Source for Programmer using a serial com port.

Console operation edit

  • programmer com_port_number con

Sends input from keys to the serial interface and displays received data.

Read memory edit

  • programmer com_port_number read {prgm|data} file number_of_words

Reads first number_of_words words of program or data memory and writes file.

Write specific memory edit

  • programmer com_port_number write {prgm|data} file [max_number_of_words]

Writes a maximum of max_number_of_words words of program or data memory from file. If max_number_of_words is omitted it writes the whole file.

Write whole program edit

  • programmer com_port_number writeall basename

Writes basename.mif to program memory and basename_data.mif to data memory.

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