Answer:

You would like:

length( string1 ) + length( string2 )   =   length( concat( string1, string2) )

If the null at the end of each string counted as part of its length, then this would be false, because the combined string has only one null (at the end) but there are two nulls in the two original strings.

Program continued

There are several ways to do what the second box of the chart calls for: "point at the first character". In a few chapters, doing this will be much easier. But, for now, remember that the data section starts at the address 0x10000000. The top halfword of this is 0x1000. This is loaded into the top halfword of the base register with lui

 

## strlen.asm 
## 
## Count the characters in a string 
## 
## Registers: 
##  $8 -- count 
##  $9 -- pointer to the char 
## $10 -- the char (in low order byte) 

.text 
.globl main 

# Initialize 

main: 
      ori $8,$0,0           # count = 0 
      lui $9,0x1000         # point at first char 
  
# while not ch==null do 
  
loop: 
       lbu $10,($9)    # get the char 
       
       sll   $0,$0,0        # load delay slot

        $10,$0,done    # exit loop if char == null 
       
       sll   $0,$0,0        # branch delay slot
   
       . . .
   
       j loop               # finish 
       sll   $0,$0,0        # branch delay slot

done:  sll $0,$0,0          # target for branch 

.data 
string: .asciiz "Time is the ghost of space."

Answer:

Program continued

QUESTION 4: