程序代写代做代考 C computer architecture Java mips assembly UCCD1133

程序代写 CS代考 / computer architecture, C语言代写, Java代写代考, MIPS汇编代写代考

UCCD1133
Introduction to Computer Organisation and Architecture
Chapter 4
Computer Architecture and Organisation Fundamental
Slides adapted from http://booksite.elsevier.com
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Disclaimer
❑ This slide may contain copyrighted material of which has not been specifically authorized by the copyright owner. The use of copyrighted materials are solely for educational purpose. If you wish to use this copyrighted material for other purposes, you must first obtain permission from the original copyright owner.
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Chapter 4 – 3
MIPS PROGRAMMING (PART 1)
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Programming
• High-level languages:
– e.g., C, Java, Python
– Written at higher level of abstraction
• Common high-level software constructs:
– if/else statements
– for loops
– while loops
– arrays
– function calls
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Instructions: Logical
• Instructions for bitwise manipulation
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Instructions: Logical
• and, or, xor, nor
– and: useful for masking bits
Masking all but the least significant byte of a value: 0xF234012F AND 0x000000FF = 0x0000002F
– or: useful for combining bit fields
Combine 0xF2340000 with 0x000012BC:
0xF2340000 OR 0x000012BC = 0xF23412BC
– nor: useful for inverting bits: ANOR$0=NOTA
• andi, ori, xori
– 16-bit immediate is zero-extended (not sign-extended)
– nori not needed
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Instructions: Logical Example 1
$s1 $s2
Source Registers
1111
1111
1111
1111 0000
0000
0000
0000
0100
0110
1010
0001 1111
0000
1011
0111
Assembly Code
and $s3, $s1, $s2 $s3
or $s4, $s1, $s2 $s4 xor $s5, $s1, $s2 $s5 nor $s6, $s1, $s2 $s6
Result
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Instructions: Logical Example 1
Source Registers
1111
1111
1111
1111 0000
0000
0000
0000
$s1 $s2
0100
0110
1010
0001 1111
0000
1011
0111
Assembly Code
and $s3, $s1, $s2 $s3
or $s4, $s1, $s2 $s4 xor $s5, $s1, $s2 $s5 nor $s6, $s1, $s2 $s6
Result
0100
0110
1010
0001 0000
0000
0000
0000
1111
1111
1111
1111 1111
0000
1011
0111
1011
1001
0101
1110 1111
0000
1011
0111
0000
0000
0000
0000 0000
1111
0100
1000
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Instructions: Logical Example 2
0000
0000
0000
0000
0000
0000
1111
1111
$s1 imm
Source Values
zero-extended
Result
0000
0000
0000
0000
1111
1010
0011
0100
Assembly Code
andi $s2, $s1, 0xFA34 $s2
ori $s3, $s1, 0xFA34 xori $s4, $s1, 0xFA34 $s4
$s3
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Instructions: Logical Example 2
0000
0000
0000
0000
0000
0000
1111
1111
$s1 imm
Source Values
zero-extended
Result
0000
0000
0000
0000
1111
1010
0011
0100
Assembly Code
andi $s2, $s1, 0xFA34 $s2
0000
0000
0000
0000
0000
0000
0011
0100
0000
0000
0000
0000
1111
1010
1111
1111
0000
0000
0000
0000
1111
1010
1100
1011
ori $s3, $s1, 0xFA34 xori $s4, $s1, 0xFA34 $s4
$s3
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Shift Instructions
• sll(shiftleftlogical)
– Shift left and fill with 0 bits
– sll by i bits multiplies by 2i
– Example: sll $t0, $t1, 5 # $t0 <= $t1 << 5 • Srl(shiftrightlogical) - Shift right and fill with 0 bits - srl by i bits divides by 2i (unsigned only) - Example: srl $t0, $t1, 5 # $t0 <= $t1 >> 5
• sra(shiftrightarithmetic)
Example: sra $t0, $t1, 5 # $t0 <= $t1 >>> 5
• shamt: how many positions to shift
6 bits 5 bits 5 bits 5 bits 5 bits 6 bits
op
rs
rt
rd
shamt
funct
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Shift Instructions
Assembly Code
op
Field Values
rs
rt
rd
shamt funct
0
0
17
8
2
0
0
0
17
18
2
2
0
0
17
19
2
3
sll $t0, $s1, 2
srl $s2, $s1, 2
sra $s3, $s1, 2
op
rs
rt
rd
shamt funct
6 bits
5 bits
5 bits
5 bits
5 bits
6 bits
Machine Code
000000
00000
10001
01000
00010
000000
000000
00000
10001
10010
00010
000010
000000
00000
10001
10011
00010
000011
(0x00114080) (0x00119082) (0x00119883)
6 bits
5 bits
5 bits
5 bits
5 bits 6 bits
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Generating Constants
•
16-bit constants • use addi:
C Code
/* int is a 32-bit signed word */
int a = 0x4f3c;
•
32-bit constants
• use load upper immediate (lui) and ori:
C Code
int a = 0xFEDC8765;
MIPS assembly code
# $s0 = a
lui $s0, 0xFEDC
ori $s0, $s0, 0x8765
MIPS assembly code
# $s0 = a
addi $s0, $0, 0x4f3c
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Multiplication, Division
• Special registers: lo, hi
• 32 × 32 multiplication, 64 bit result – mult $s0, $s1
– Result in {hi, lo}
• 32-bit division, 32-bit quotient, remainder
– div $s0, $s1
– Quotient in lo
– Remainder in hi
• Moves from lo/hi special registers
– mflo $s2 – mfhi $s3
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Branching
• Execute instructions out of sequence • Types of branches:
• Conditional
• Branch to a labeled instruction if a condition is true. Otherwise, continue sequentially.
• branch if equal (beq rs rt L1)
• If (rs == rt) branch to instruction labeled L1 • branchifnotequal(bnersrtL1)
• If (rs != rt) branch to instruction labeled L1
• Unconditional • jump (j)
• jumpregister(jr)
• jumpandlink(jal)
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Instructions: Conditional Branch Branch on equal (beq)
# MIPS assembly
addi $s0, $0, 4
addi $s1, $0, 1
sll $s1,$s1,2
beq $s0, $s1, target # branch is taken addi $s1, $s1, 1 # not executed sub $s1, $s1, $s0 # not executed
target: # label
add $s1,$s1,$s0 #$s1=4+4=8
Labels indicate instruction location. They can’t be reserved words and must be followed by colon (:)
# $s0 = 0 + 4 = 4 # $s1 = 0 + 1 = 1
#$s1=1<<2=4 Page <16>

Instructions: Conditional Branch Branch on not equal (bne)
# MIPS assembly
addi $s0,$0,4
addi $s1,$0,1
sll $s1,$s1,2
bne $s0, $s1, target addi $s1,$s1,1
sub $s1, $s1, $s0
target:
add $s1, $s1, $s0
#$s0=0+4=4 #$s1=0+1=1 #$s1=1<<2=4 # branch not taken #$s1=4+1=5 # $s1 = 5 – 4 = 1 # $s1 = 1 + 4 = 5 Page <17>

Instructions: Unconditional Jump Jump (j L1)
– Unconditional jump to instruction labeled L1
# MIPS assembly
addi $s0, $0, 4 addi $s1, $0, 1
j target
sra $s1, $s1, 2 addi $s1, $s1, 1 sub $s1, $s1, $s0
target:
add $s1, $s1, $s0
# $s0 = 4
# $s1 = 1
# jump to target # not executed # not executed # not executed
# $s1 = 1 + 4 = 5
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High-Level Code Constructs
• if statements
• if/else statements • while loops
• for loops
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If Statement
C Code
if (i == j)
f = g + h;
f = f – i;
MIPS assembly code
# $s0 = f, $s1 = g, $s2 = h # $s3 = i, $s4 = j
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If Statement
C Code
if (i == j)
f = g + h;
f = f – i;
MIPS assembly code
# $s0 = f, $s1 = g, $s2 = h # $s3 = i, $s4 = j
Else:
bne $s3, $s4, Else
add $s0, $s1, $s2
sub $s0, $s0, $s3
Assembly tests opposite case (i != j) of high-level code (i == j)
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If/Else Statement
C Code
if (i == j)
f = g + h;
else
f = f – i;
MIPS assembly code
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If/Else Statement
C Code
if (i == j)
f = g + h;
else f=f–i;
MIPS assembly code
# $s0 = f, $s1 = g, $s2 = h # $s3 = i, $s4 = j
bne $s3, $s4, Else add $s0, $s1, $s2 j Exit
Else: sub$s0,$s0,$s3 Exit:
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While Loops
C Code
// determines the power //ofxsuchthat2x =128 int pow = 1;
intx =0;
while (pow != 128) {
pow = pow * 2;
x = x + 1;
}
MIPS assembly code
Assembly tests for the opposite case (pow == 128) of the C code (pow != 128).
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While Loops
C Code
// determines the power //ofxsuchthat2x =128 int pow = 1;
intx =0;
while (pow != 128) {
pow = pow * 2;
x = x + 1;
}
MIPS assembly code
# $s0 = pow, $s1 = x
addi $s0, $0, 1
add $s1, $0, $0
addi $t0, $0, 128
while: beq $s0, $t0, Exit
sll $s0, $s0, 1
addi $s1, $s1, 1
j while Exit:
Assembly tests for the opposite case (pow == 128) of the C code (pow != 128).
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For Loops
for (initialization; condition; loop operation)
statement
• initialization: executes before the loop begins
• condition: is tested at the beginning of each iteration
• loop operation: executes at the end of each iteration • statement: executes each time the condition is met
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For Loops
High-level code
// add the numbers from 0 to 9 int sum = 0;
int i;
for (i=0; i!=10; i = i+1) {
sum = sum + i;
}
MIPS assembly code
# $s0 = i, $s1 = sum
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For Loops
C Code
// add the numbers from 0 to 9 int sum = 0;
int i;
for (i=0; i!=10; i = i+1) {
sum = sum + i;
}
MIPS assembly code
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For Loops
C Code
// add the numbers from 0 to 9 int sum = 0;
int i;
for (i=0; i!=10; i = i+1) {
sum = sum + i;
}
MIPS assembly code
# $s0 = i, $s1 = sum addi $s1, $0, 0
for:
add $s0, $0, $0
addi $t0, $0, 10
beq $s0, $t0, done
add $s1, $s1, $s0
addi $s0, $s0, 1
j for done:
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More conditional operations
• Set result to 1 if a condition is true • Otherwise, set to 0
• sltrd,rs,rt
• if (rs < rt) rd = 1; else rd = 0 • slti rt, rs, constant • if (rs < constant) rt = 1; else rt = 0 • Use in combination with beq, bne slt $t0, $s1, $s2 # if ($s1 < $s2) bne $t0, $zero, L # branch to L Page <30>

Less Than Comparison
C Code
// add the powers of 2 from 1 // to 100
int sum = 0;
int i;
for (i=1; i < 101; i = i*2) { sum = sum + i; } MIPS assembly code Page <31>

Less Than Comparison
C Code
// add the powers of 2 from 1 // to 100
int sum = 0;
int i;
for(i=1;i<101;i=i*2){ sum = sum + i; } MIPS assembly code # $s0 = i, $s1 = sum addi $s1, $0, 0 addi $s0, $0, 1 addi $t0, $0, 101 loop: slt $t1, $s0, $t0 beq $t1,$0,done add $s1, $s1, $s0 sll $s0, $s0, 1 j loop done: $t1=1 if i<101 Page <32>

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