Holooly Plus Logo
Holooly Plus Logo

Question 2.7.4: Bounds Check Shortcut Use this shortcut to reduce an index-o......

Bounds Check Shortcut

Use this shortcut to reduce an index-out-of-bounds check: jump to IndexOutOfBounds if \$s1 ≥ \$t2 or if $s1 is negative.

Step-by-Step
The 'Blue Check Mark' means that this solution was answered by an expert.
Learn more on how do we answer questions.
Report Answer

Th e checking code just uses u to do both checks:

sltu $t0, $s1, $t2 # $t0= 0 if $s1 >= length or $s1 < 0
beq $t0, $zero, IndexOutOfBounds #if  bad, goto Error

Related Answered Questions

Question: 2.10.4

Decoding Machine Code What is the assembly language statement corresponding to this machine instruction? 00af8020hex ...

Verified Answer:

The first step in converting hexadecimal to binary...
Question: 2.3.3

Compiling Using Load and Store Assume variable h is associated with register $s2 and the base address of the array A is in $s3. What is the MIPS assembly code for the C assignment statement below? A[12] = h + A[8]; ...

Verified Answer:

Although there is a single operation in the C stat...
Question: 2.10.3

Branching Far Away Given a branch on register $s0 being equal to register $s1, beq $s0, $s1, L1 replace it by a pair of instructions that off ers a much greater branching distance. ...

Verified Answer:

Th ese instructions replace the short-address cond...
Question: 2.10.2

Showing Branch Offset in Machine Language The while loop on pages 92-93 was compiled into this MIPS assembler code: Loop: s11 $t1, $s3, 2 #Temp reg $t1 = 4 * i add $t1, $t1, $s6 #$t1 = address of save[i] 1w $t0, 0($t1) #Temp reg $to = save[i] bne $to, $s5, Exit #go to Exit if save[i] ≠ k addi $s3, ...

Verified Answer:

The assembled instructions and their addresses are...
Question: 2.10.1

Loading a 32-Bit Constant What is the MIPS assembly code to load this 32-bit constant into register $s0? 0000 0000 0011 1101 0000 1001 0000 0000 ...

Verified Answer:

First, we would load the upper 16 bits, which is 6...
Question: 2.9.2

Compiling a String Copy Procedure, Showing How to Use C Strings The procedure strcpy copies string y to string x using the null byte termination convention of C: void strcpy (char x[ ], char y[ ]) { int i; i = 0; while ((x[i] = y[i]) != ‘\0’) /* copy & test byte */i += 1; } What is the MIPS ...

Verified Answer:

Below is the basic MIPS assembly code segment. Ass...
Question: 2.9.1

ASCII versus Binary Numbers We could represent numbers as strings of ASCII digits instead of as integers. How much does storage increase if the number 1 billion is represented in ASCII versus a 32-bit integer? ...

Verified Answer:

One billion is 1,000,000,000, so it would take 10 ...
Question: 2.8.2

Compiling a Recursive C Procedure, Showing Nested Procedure Linking  Let’s tackle a recursive procedure that calculates factorial: int fact (int n) { if (n < 1) return (1); else return (n * fact(n – 1));} What is the MIPS assembly code? ...

Verified Answer:

Th e parameter variable n corresponds to the argum...
Question: 2.8.1

Compiling a C Procedure That Doesn’t Call Another Procedure Let’s turn the example on page 65 from Section 2.2 into a C procedure: int leaf_example (int g, int h, int i, int j) { int f; f = (g + h) – (i + j); return f; } What is the compiled MIPS assembly code? ...

Verified Answer:

Th e parameter variables g, h, i, and j correspond...
Question: 2.7.3

Signed versus Unsigned Comparison Suppose register $s0 has the binary number 1111 1111 1111 1111 1111 1111 1111 1111two and that register $s1 has the binary number 0000 0000 0000 0000 0000 0000 0000 0001two What are the values of registers $t0 and $t1 after these two instructions? slt $t0, $s0, ...

Verified Answer:

The value in register $s0 represents -1_{te...