计算机组成第三周第一题

00 题目

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。


A   Alpha   N   November    1   First   a   alpha   n   november
B   Bravo   O   Oscar       2   Second  b   bravo   o   oscar
C   China   P   Paper       3   Third   c   china   p   paper
D   Delta   Q   Quebec      4   Fourth  d   delta   q   quebec
E   Echo    R   Research    5   Fifth   e   echo    r   research
F   Foxtrot S   Sierra      6   Sixth   f   foxtrot s   sierra
G   Golf    T   Tango       7   Seventh g   golf    t   tango
H   Hotel   U   Uniform     8   Eighth  h   hotel   u   uniform
I   India   V   Victor      9   Ninth   i   india   v   victor
J   Juliet  W   Whisky      0   zero    j   juliet  w   whisky
K   Kilo    X   X-ray                   k   kilo    x   x-ray
L   Lima    Y   Yankee                  l   lima    y   yankee
M   Mary    Z   Zulu                    m   mary    z   zulu

01 mips.1.asm

		.data
number_words: 	.asciiz 
          	" zero\r\n"," First\r\n"," Second\r\n"," Third\r\n", " Fourth\r\n", " Fifth\r\n", " Sixth\r\n", " Seventh\r\n", " Eighth\r\n", " Ninth\r\n"
number_offset: 	.word
	  	0, 8, 17, 27, 36, 46, 55, 64, 75, 85

uppercase_words: .asciiz
		" Alpha\r\n", " Bravo\r\n", " China\r\n", " Delta\r\n", " Echo\r\n", " Foxtrot\r\n", " Golf\r\n", " Hotel\r\n", " India\r\n", " Juliet\r\n", " Kilo\r\n", " Lima\r\n", " Mary\r\n", " November\r\n", " Oscar\r\n", " Paper\r\n", " Quebec\r\n", " Research\r\n", " Sierra\r\n", " Tango\r\n", " Uniform\r\n", " Victor\r\n", " Whisky\r\n", " X-ray\r\n", " Yankee\r\n", " Zulu\r\n"
uppercase_offset: .word
		0, 9, 18, 27, 36, 44, 55, 63, 72, 81, 91, 99, 107, 115, 127, 136, 145, 155, 167, 177, 186, 197, 207, 217, 226, 236

lowercase_words: .asciiz
		" alpha\r\n", " bravo\r\n", " china\r\n", " delta\r\n", " echo\r\n", " foxtrot\r\n", " golf\r\n", " hotel\r\n", " india\r\n", " juliet\r\n", " november\r\n", " oscar\r\n", " paper\r\n", " quebec\r\n", " research\r\n", " sierra\r\n", " tango\r\n", " uniform\r\n", " victor\r\n", " whisky\r\n", " kilo\r\n", " lima\r\n", " mary\r\n", " x-ray\r\n", " yankee\r\n", " zulu\r\n"
lowercase_offset: .word
		0, 9, 18, 27, 36, 44, 55, 63, 72, 81, 91, 103, 112, 121, 131, 143, 153, 162, 173, 183, 193, 201, 209, 217, 226, 236
		.text
		.globl main
main: 
	# read a character
	li $v0, 12
	syscall
	beq $v0, 63, quit # if $v0 == '?' then quit
	
	## check number begin
	# check if the character is less than '0'
	sub $t0, $v0, 48 # $t0 = $v0(the character we just received from input) - 48
	bltz $t0, unknown_character  # Branch on less than zero
	# check if the character is less than or euqal to '9'
	sub $t0, $v0, 57
	blez $t0, print_number_word
	## check number end
	
	## check uppercase begin
	sub $t0, $v0, 65
	bltz $t0, unknown_character  # Branch on less than zero
	# check if the character is less than or euqal to 'Z'
	sub $t0, $v0, 90
	blez $t0, print_uppercase_word
	## check uppercase end
	
	## check lowercase begin
	sub $t0, $v0, 97
	bltz $t0, unknown_character  # Branch on less than zero
	# check if the character is less than or euqal to 'z'
	sub $t0, $v0, 122
	blez $t0, print_lowercase_word
	## check lowercase end
	
	
	
	j unknown_character

print_number_word:
	sub $t0, $v0, 48 # get number
	sll $t0, $t0, 2 # for 1 word is equal to 2 bytes
	la $t1, number_offset
	add $t1, $t1, $t0
	lw $t1, ($t1)
	
	la $a0, number_words
	add $a0, $a0, $t1
	li $v0, 4
	syscall
	j main

print_uppercase_word:
	sub $t0, $v0, 65
	sll $t0, $t0, 2 # for 1 word is equal to 2 bytes
	la $t1, uppercase_offset
	add $t1, $t1, $t0
	lw $t1, ($t1)
	
	la $a0, uppercase_words
	add $a0, $a0, $t1
	li $v0, 4
	syscall
	j main

print_lowercase_word:
	sub $t0, $v0, 97
	sll $t0, $t0, 2 # for 1 word is equal to 2 bytes
	la $t1, lowercase_offset
	add $t1, $t1, $t0
	lw $t1, ($t1)
	
	la $a0, lowercase_words
	add $a0, $a0, $t1
	li $v0, 4
	syscall
	j main

unknown_character:
	li $a0, 42 # '*'
	li $v0, 11 # print a character
	syscall
	j main

quit:
	li $v0, 10 # exit
	syscall

02 参考资料.md

1. MIPS Instruction Reference
2. MIPS syscall functions
3. ASCII Table
4. 计算机组成 - Coursera