MIPS 汇编 第一题：用系统功能调用实现简单输入输出

版权声明：作者：巴伐利亚酒仙 https://blog.csdn.net/weixin_39062811/article/details/88925892

Cousera MIPS 汇编程序设计

第一题：用系统功能调用实现简单输入输出

利用系统功能调用从键盘输入，转换后在屏幕上显示，具体要求如下：

(1) 如果输入的是字母（A_{Z，区分大小写）或数字（0}9），则将其转换成对应的英文单词后在屏幕上显示，对应关系见下表

(2) 若输入的不是字母或数字，则在屏幕上输出字符“*”，

(3) 每输入一个字符，即时转换并在屏幕上显示，

(4) 支持反复输入，直到按“?”键结束程序。

.data
Upperalphabet:
    .asciiz " Alpha\n"," Bravo\n"," China\n"," Delta\n"," Echo\n"," Foxtrot\n"," Golf\n"," Hotel\n",
    " India\n"," Juliet\n"," Kilo\n"," Lima\n"," Mary\n"," November\n"," Oscar\n"," Paper\n"," Quebec\n",
    " Research\n"," Sierra\n"," Tango\n"," Uniform\n"," Victor\n"," Whisky\n"," X-ray\n"," Yankee\n"," Zulu\n"
Loweralphabet:
    .asciiz " alpha\n"," bravo\n"," china\n"," delta\n"," echo\n"," foxtrot\n"," golf\n"," hotel\n"," india\n",
    " juliet\n"," kilo\n"," lima\n"," mary\n"," november\n"," oscar\n"," paper\n"," quebec\n"," research\n",
    " sierra\n"," tango\n"," uniform\n"," victor\n"," whisky\n"," x-ray\n"," yankee\n"," zulu\n"
Number:		.asciiz "zero ", "one ", "two ", "three ", "four ", "five ", "six ", "seven ","eight ","nine "
alphabet_offset: .word 0,8,16,24,32,39,49,56,64,72,81,88,95,102,113,121,129,138,149,158,166,176,185,194,202,211
stop:	.ascii "Stop"
number_offset:	.word 0,6,11,16,23,29,35,40,47,54
.text 
main:
	li $v0, 12
	syscall 
	sub  $t0, $v0, 63   # is ?
	beqz $t0, exit
	
	sub  $t0, $v0, 48   # is less than 0?
	slt  $s0, $t0, $0   #if t0<0 then s0 = 1
	bnez $s0, none
	
	 # is number?
	sub  $t1, $t0, 10
	slt  $s1, $t1, $0
	bnez $s1, getnum
	
	 # is capital?
 	sub  $t1, $v0, 91
 	slt  $s3, $t1, $0 # if v0 <= 'Z' then s3 = 1
 	sub  $t2, $v0, 64 
 	sgt  $s4, $t2, $0 # if v0 >='A' then s4 = 1
 	and  $s0, $s3, $s4 # if s3 == 1 && s4 == 1 
 	bnez $s0, getupword 
 
 	# is lower case?
 	sub  $t1, $v0, 123
 	slt  $s3, $t1, $0 # if v0 <= 'z' then s3 = 1
 	sub  $t2, $v0, 96  
 	sgt  $s4, $t2, $0 # if v0 >= 'a' then s4 = 1
 	and  $s0, $s3, $s4
 	bnez $s0, getlwword
 	j none
	
	
	
	
getnum:
	add $t1, $t1, 10
	sll $t1, $t1, 2
	la  $s0, number_offset
	add $s0, $s0, $t1
	lw  $s1, ($s0)
	la  $a0, Number
	add $a0, $a0, $s1
	li  $v0, 4
	syscall
	j main
	
getupword:
	sub $t2, $t2, 1
 	sll $t2, $t2, 2
 	la  $s0, alphabet_offset
 	add $s0, $s0, $t2
 	lw  $s1, ($s0)
 	la  $a0, Upperalphabet
 	add $a0, $s1, $a0
 	li  $v0, 4
 	syscall
 	j main
 	
getlwword:
	sub $t2, $t2, 1
 	sll $t2, $t2, 2
 	la  $s0, alphabet_offset
 	add $s0, $s0, $t2
 	lw  $s1, ($s0)
 	la  $a0, Loweralphabet
 	add $a0, $s1, $a0
 	li  $v0, 4
 	syscall
 	j main
none:
	and $a0, $0, $0
	add $a0, $a0, 42    # print *
	li  $v0, 11
	syscall 
	j main
exit:
	add $a0, $0, '\n'
	li  $v0, 11
	syscall 
	la  $a0, stop
	li  $v0, 4
	syscall

输出结果

1one 2two 3three 4four 
*s sierra
f foxtrot
g golf
B Bravo
K Kilo
O Oscar
?
Stop