MIPS的add指令能用到shift-left-2硬件单元吗

是的，MIPS的add指令可以利用shift-left-2硬件单元。在MIPS架构中，shift-left-2硬件单元用于将一个立即数左移两位，并将其作为地址偏移量添加到使用register(通常是$t寄存器)中的内容中，以生成要访问的内存地址。因此，使用shift-left-2 硬件单元可以有效地将立即数与寄存器的内容相加，并生成正确的内存地址。

相关问题

Write MIPS assembly language program for shift logical left.

Sure, here's an example MIPS assembly language program for shift logical left:

.data
input: .word 0x0000000F		# 4-bit input value

.text
.globl main
main:
	lw $a0, input			# load input value into $a0
	sll $a0, $a0, 2			# shift $a0 left by 2 bits (multiply by 4)
	
	# output result
	li $v0, 1				# set $v0 to print integer
	move $a0, $a0			# move result into $a0 (for printing)
	syscall					# print result
	
	# exit program
	li $v0, 10				# set $v0 to exit
	syscall					# exit program

In this program, we start by defining a 4-bit input value in the `.data` section. Then, in the `.text` section, we load the input value into register `$a0` using the `lw` instruction.

Next, we use the `sll` instruction to shift `$a0` left by 2 bits (multiply by 4). The `sll` instruction takes three operands: the destination register (in this case, `$a0`), the source register (also `$a0`), and the number of bits to shift by (2 in this case).

After performing the shift, we output the result using the `li`, `move`, and `syscall` instructions. Finally, we exit the program using the `li`, `syscall` instructions.

MIPS li $v0, -2 scancode 2是什么意思

MIPS li $v0, -2 scancode 2 是一条 MIPS 指令，它的功能是将寄存器 $v0 的内容设置为 -2，然后调用系统调用编号为 2 的输入函数，等待用户在键盘上输入一个字符，并将这个字符的 ASCII 码值存储到 $v0 寄存器中。