ARM 汇编(sum, gcd, lcm, sort, max, min, strcpy)
1 一位数组按某种规律求和
1.1 一维数组求和
AREA ARRAYSUM, CODE, READONLY
ENTRY
START
LDR R0, =src
MOV R1, #0
MOV R3, #0
LOOP
LDR R2, [R0]
ADD R0, R0, #4
ADD R3, R3, #1
ADD R1, R1, R2
CMP R3, #len
BNE LOOP
STOP
MOV R5, R1
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA ARRAY, DATA, READONLY
src DCD 1, 2, 3, 4, 5 ,6 ,7, 8, 9, 10
len EQU 10
END
1.2 求一维数组中奇数的和
AREA ARRAYSUM, CODE, READONLY
ENTRY
START
LDR R0, =src
MOV R1, #0
MOV R3, #0
LOOP
LDR R2, [R0]
ADD R0, R0, #4
ADD R3, R3, #1
AND R4, R2, #1
CMP R4, #0
ADDNE R1, R1, R2
CMP R3, #len
BNE LOOP
STOP
MOV R5, R1
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA ARRAY, DATA, READONLY
src DCD 1, 2, 3, 4, 5 ,6 ,7, 8, 9, 10
len EQU 10
END
1.3 求一维数组中的偶数和
AREA ARRAYSUM, CODE, READONLY
ENTRY
START
LDR R0, =src
MOV R1, #0
MOV R3, #0
LOOP
LDR R2, [R0]
ADD R0, R0, #4
ADD R3, R3, #1
AND R4, R2, #1
CMP R4, #1
ADDNE R1, R1, R2
CMP R3, #len
BNE LOOP
STOP
MOV R5, R1
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA ARRAY, DATA, READONLY
src DCD 1, 2, 3, 4, 5 ,6 ,7, 8, 9, 10
len EQU 10
END
2 求两个数的最大公约数
int gcd(int a, int b)
{
return b ? gcd(b, a % b) : a;
}
AREA SOLVEGCD, CODE, READONLY
ENTRY
START
MOV R0, #20;a
MOV R1, #50;b
GCD
CMP R0, R1;比较两个数的大小，大的数放 R0，小的数放 R1，下三行表示交换数字的过程
MOVLS R2, R1
MOVLS R1, R0
MOVLS R0, R2
SUB R0, R0, R1;使用更相减损法求最大公约数
CMP R0, R1;若减数等于差，则得到最大公约数，最大公约数为差
BNE GCD
STOP
MOV R2, R1;将结果保存到 R2
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
END
3 求两个数的最小公倍数
lcm ( a , b ) = a × b gcd(a,b) \operatorname{lcm}(a,b)=\frac{a\times b}{\operatorname{gcd(a,b)}} lcm(a,b)=gcd(a,b)a×b
AREA SOLVELCM, CODE, READONLY
ENTRY
START
MOV R0, #20;a
MOV R1, #50;b
MUL R3, R0, R1;a * b
MOV R4, #0;保存 LCM 计算结果
GCD
CMP R0, R1
MOVLS R2, R1
MOVLS R1, R0
MOVLS R0, R2
SUB R0, R0, R1
CMP R0, R1
BNE GCD
;模拟除法
LCM
SUB R3, R3, R0
ADD R4, R4, #1
CMP R3, #0;判断是否除尽
BNE LCM
STOP
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
END
4 对一维数组进行排序
冒泡排序
AREA SORT, CODE, READONLY
ENTRY
START
LDR R5, =src
MOV R3, #1
;外层循环
LOOPI
LDR R0, =src
MOV R4, #1
;内层循环
LOOPJ
LDR R1, [R0]
LDR R2, [R0, #4]
CMP R1, R2
STRGT R2, [R0]
STRGT R1, [R0, #4]
ADD R0, R0, #4
ADD R4, R4, #1
CMP R4, #len
BNE LOOPJ
ADD R3, R3, #1
CMP R3, #len
BNE LOOPI
STOP
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA STRING, DATA, READONLY
src DCD 1, 5, 4, 6, 3, 8, 9, 2, 7, 10
len EQU 10
END
5 求一维数组中的最大值
AREA SOLVEMAX, CODE, READONLY
ENTRY
START
LDR R0, =src;将数组的首地址放到R0
LDR R2, [R0];取数组的第一个值
MOV R1, #1;R1 用于记录访问了数组多少个元素了
LOOP
ADD R0, R0, #4;更新地址
LDR R3, [R0];取值
ADD R1, R1, #1;计数加一
CMP R3, R2;比较两个数的大小
MOVHI R2, R3;如果 R3 大于 R2，则将 R2 的值设为 R3
CMP R1, #len;判断是否遍历完毕
BNE LOOP
STOP
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA ARRAY, DATA, READONLY
src DCD 4, 5, 2, 3, 1, 6, 4, 3
len EQU 8
END
6 求一维数组中的最小值
AREA SOLVEMIN, CODE, READONLY
ENTRY
START
LDR R0, =src
MOV R1, #1
LDR R2, [R0]
LOOP
ADD R0, R0, #4
LDR R3, [R0]
ADD R1, R1, #1
CMP R2, R3;相比于求最大值的代码，唯一改动的地方
MOVHI R2, R3
CMP R1, #len
BNE LOOP
STOP
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA ARRAY, DATA, READONLY
src DCD 4, 5, 2, 3, 1, 6, 4, 3
len EQU 8
END
7 字符串的复制
AREA SOLVEMAX, CODE, READONLY
ENTRY
START
LDR R2, =src
LDR R3, =des
LOOP
LDRB R4, [R2], #1
STRB R4, [R3], #1
CMP R4, #0
BNE LOOP
STOP
MOV R0, #24
LDR R1, =0x0300000
SWI 0X123456
AREA STRING, DATA, READONLY
src DCB "SWPUACM\0"
des DCB ""
END