汇编语言ARM Cortex-A53中的随机数生成器

Question

所以我必须使用raspberry pi 3和gpio在程序集中构建一个骰子游戏。我已经构建了大部分内容，但我遇到的是随机数部分的范围部分。当用户按下按钮时，我需要数字介于1-6之间。我看过其他例子，但其中一个似乎对我有帮助。使用线性先天发电机似乎过度杀死。

.text
.global main

main:
    push {lr}
    bl wiringPiSetup

     push {lr}
        bl rand // will get a random number and put it in r0
// some wher in here is were you need to do the math to make the number
// fall inbwtween 0- 5 +1 to the result
        mov r1,r0 // will take r0 value and put it in to r1
        ldr r0,=pattern // will take the vaule in patter and give it to r0
        bl printf
        pop {pc}
.data
        pattern: .asciz  "%d\n" 



cmp r0, #1
//bleq moves you back to where you camefrom
beq roll1

cmp r0, #2
beq roll2

cmp r0, #3
beq roll3

cmp r0, #4
beq roll4

cmp r0, #5
beq roll5

cmp r0, #6
beq roll6

roll1:
    // this is to tell the singal to go out
        mov r0, #0  // this is writing to pin 17
        mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
        bl pinMode
        // this is to tell the pins to power up
        mov r0, #0
        mov r1, #0
        bl digitalWrite

roll2:
    // this is to tell the singal to go out
        mov r0, #0  // this is writing to pin 17
        mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
        bl pinMode
        // this is to tell the pins to power up
        mov r0, #0
        mov r1, #0
        bl digitalWrite

        mov r0, #2  // this is writing to pin 27
        mov r1, #0
        bl pinMode

        mov r0, #2
        mov r1, #0
        bl digitalWrite

roll3:
    // this is to tell the singal to go out
        mov r0, #0  // this is writing to pin 17
        mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
        bl pinMode
        // this is to tell the pins to power up
        mov r0, #0
        mov r1, #0
        bl digitalWrite

        mov r0, #2  // this is writing to pin 27
        mov r1, #0
        bl pinMode

        mov r0, #2
        mov r1, #0
        bl digitalWrite

        mov r0, #3 // this is writing to pin 22
        mov r1, #0
        bl pinMode

        mov r0, #3
        mov r1, #0
        bl digitalWrite

roll4:
    // this is to tell the singal to go out
        mov r0, #0  // this is writing to pin 17
        mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
        bl pinMode
    // this is to tell the pins to power up
        mov r0, #0
        mov r1, #0
        bl digitalWrite

        mov r0, #2  // this is writing to pin 27
        mov r1, #0
        bl pinMode

        mov r0, #2
        mov r1, #0
        bl digitalWrite

        mov r0, #3 // this is writing to pin 22
        mov r1, #0
        bl pinMode

        mov r0, #3
        mov r1, #0
        bl digitalWrite

        mov r0, #21  // this is writing to pin 5
        mov r1, #0
        bl pinMode

        mov r0, #21
        mov r1, #0
        bl digitalWrite

roll5:
    // this is to tell the singal to go out
        mov r0, #0  // this is writing to pin 17
        mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
        bl pinMode
// this is to tell the pins to power up
        mov r0, #0
        mov r1, #0
        bl digitalWrite

        mov r0, #2  // this is writing to pin 27
        mov r1, #0
        bl pinMode

        mov r0, #2
        mov r1, #0
        bl digitalWrite

        mov r0, #3 // this is writing to pin 22
        mov r1, #0
        bl pinMode

        mov r0, #3
        mov r1, #0
        bl digitalWrite

        mov r0, #21  // this is writing to pin 5
        mov r1, #0
        bl pinMode

        mov r0, #21
        mov r1, #0
        bl digitalWrite

        mov r0, #22  // this is wriritin  to pin 6
        mov r1, #0
        bl pinMode

        mov r0, #22
        mov r1, #0
        bl digitalWrite


roll6:
// this is to tell the singal to go out
    mov r0, #0  // this is writing to pin 17
    mov r1, #0  //  if it is a one you want power to go to it if not then enter 0
    bl pinMode
// this is to tell the pins to power up
    mov r0, #0
    mov r1, #0
    bl digitalWrite

    mov r0, #2  // this is writing to pin 27
    mov r1, #0
    bl pinMode

    mov r0, #2
    mov r1, #0
    bl digitalWrite

    mov r0, #3 // this is writing to pin 22
        mov r1, #0
        bl pinMode

        mov r0, #3
        mov r1, #0
        bl digitalWrite

    mov r0, #21  // this is writing to pin 5
        mov r1, #0
        bl pinMode

        mov r0, #21
        mov r1, #0
        bl digitalWrite

    mov r0, #22  // this is wriritin  to pin 6
        mov r1, #0
        bl pinMode

        mov r0, #22
        mov r1, #0
        bl digitalWrite

    mov r0, #23  // this is writing to pin 13
        mov r1, #0
        bl pinMode

        mov r0, #23
        mov r1, #0
        bl digitalWrite

button:
// these botton two leave them on at all times they are the power to use the button.
    mov r0, #7
        mov r1, #1
        bl pinMode

        mov r0, #7
        mov r1, #1
        bl digitalWrite

    pop {pc}
// somewhere after pop or before add a deley so that all leds can be turned off

Answer 1

如果你想使用系统调用，一个想法是调用gettimeofday系统调用，然后使用微秒的3个最高位来模拟掷骰子。您应该进行一些随机性测试，以确定这是否是一个合理的伪随机生成器。

.bss
        t:      .zero           // syscall storage
...
ldr r9,=t
...
mov r7, #78                     // <syscall name="gettimeofday" number="78"/>
ldr r0,=t                       // pointer
mov r1, #0                      // 
svc #0
ldr r0,[r9,#1]                  // microseconds in second element