从硬件编写低级语言

时间:2012-05-08 03:15:55

标签: compiler-construction low-level hardware-programming

我有兴趣了解如何在没有unix系统调用等高级函数的帮助下编译/创建一个非常简单的语言(即brainfuck)。我想在一些依赖于CPU的低级程序集中为该语言编写一个编译器,这样我就可以用简单的语言提供源代码并最终得到二进制文件。不确定这是否清楚,但基本问题是如何在没有硬件中已有的任何东西的帮助下将源转换为二进制文件。

编辑:更简洁的问题陈述......

下式给出:

- 硬件(主板/ CPU等)

NOT GIVEN:

-unix / DOS

-C / FORTRAN /任何其他语言

我如何实施像brainfuck这样的简单语言?

我知道有更多实用的编译方法,但我对此有兴趣用于教育目的。

很抱歉,如果这个问题多余或明显 - 我不是计算机科学家,所以也许我只是不知道在线找到问题解决方案的正确词汇。如果任何人可以提供关于该主题的链接或文本,将不胜感激。

4 个答案:

答案 0 :(得分:1)

查看维基百科上的描述这不是一项艰巨的任务。我可能仍然会用你知道的某种语言开始,也许不喜欢。 C是个不错的选择。文件I / O是一个小型或大型项目,具体取决于平台等。稍后担心,编译语言的“源”。对于该源中的每个字符,执行任务

> ++ptr;
< --ptr;
+ ++*ptr;
etc

然后将其转换为汇编。你只需要一个寄存器来保存ptr,几行asm来初始化数组/ ram并将寄存器/ ptr设置为开头。另一个注册来完成源代码。你只需要找8个字符,你可以if-then-else你的方式通过那些,除非有一些模式的东西,使他们更容易处理。如果你想要你可以创建一个256byte的查找表,并将其用于该指令的处理程序的地址或将它们转换为0-7的整数,并在跳转表中使用它,无论如何。

那是一个解析器,不一定是编译器。我会用C或某种高级语言编写编译器,它接受一个字节数组,即程序,对于每个输出实现该指令的asm源代码的指令,输入输出时得到一个小于字节(使用ARM asm)

add r0,#1

减号

ldr r1,[r0]
sub r1,#1
str r1,[r0]

r0是ptr寄存器而r1只是帮忙。

如果你真的反对使用像printf这样的调用,那么让这段代码的输出为字节数组,这是asm的ascii,输出每个字符a,d,d,space,r,0,逗号,#,1,cr,lf等。在asm以及一些高级语言中实现相当容易。如果你想直接使用二进制文件,那么只需输出机器代码即可。

将源字符串放入此编译器并将输出转换为某个文件然后可以执行该系统调用。如果您在同一平台上运行,则可以避免输出为文件,并且可以在某个地址构建机器代码的意义上进行自修改代码,然后在完成解析后跳转到该地址执行。

编写这个答案比用C或asm实现解决方案花了很多倍。你遇到的确切困难是什么?

答案 1 :(得分:1)

你可以很容易地将brainfuck源代码编译成DOS .COM应用程序(你还需要NASM或一些额外的代码来发出指令操作码并计算跳转)。下面是一个稍微修改过的bf解释器,变成了各种编译器:

// file: bfcompil.c

#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define MAX_CODE_SIZE 30000

char code[MAX_CODE_SIZE];
char* pc = &code[0];
char* pcEnd = &code[0];

#define MAX_DATA_SIZE 30000

char data[MAX_DATA_SIZE] = { 0 };
char* pd = &data[0];

// Structures for quick bracket matching
unsigned brStack[MAX_CODE_SIZE];
unsigned brSptr = 0;
unsigned brMatch[MAX_CODE_SIZE];

int main(int argc, char** argv)
{
  FILE* f = NULL;
  int ch;

  if (argc != 2)
  {
    fprintf(stderr, "usage:\n  bfcompil <brainfuck-source-code-file>\n"
                    "bfcompil will output NASM-compilable source code for"
                    "a DOS program\n");
    return EXIT_FAILURE;
  }

  if ((f = fopen(argv[1], "rb")) == NULL)
  {
    fprintf(stderr, "can't open file \"%s\" for reading\n", argv[1]);
    return EXIT_FAILURE;
  }

  while ((ch = getc(f)) != EOF)
  {
    if (strchr(" \t\r\n", ch) != NULL) // skip white space
    {
      continue;
    }
    else if (strchr("><+-.,[]", ch) != NULL) // store valid commands
    {
      if (pcEnd >= &code[sizeof(code)])
      {
        fprintf(stderr, "too many commands in file \"%s\", expected at most "
                        "%u commands\n", argv[1], (unsigned)sizeof(code));
        fclose(f);
        return EXIT_FAILURE;
      }

      if (ch == '[')
      {
        brStack[brSptr++] = (unsigned)(pcEnd - &code[0]);
      }
      else if (ch == ']')
      {
        if (brSptr == 0)
        {
          fprintf(stderr, "unmatched ']' in file \"%s\"\n", argv[1]);
          fclose(f);
          return EXIT_FAILURE;
        }

        brSptr--;
        brMatch[brStack[brSptr]] = (unsigned)(pcEnd - &code[0]);
        brMatch[pcEnd - &code[0]] = brStack[brSptr];
      }

      *pcEnd++ = ch;
    }
    else // fail on invalid commands
    {
      fprintf(stderr, "unexpected character '%c' in file \"%s\", valid command "
                      "set is: \"><+-.,[]\"\n", ch, argv[1]);
      fclose(f);
      return EXIT_FAILURE;
    }
  }

  fclose(f);

  if (brSptr != 0)
  {
    fprintf(stderr, "unmatched '[' in file \"%s\"\n", argv[1]);
    return EXIT_FAILURE;
  }

  if (pcEnd == &code[0])
  {
    fprintf(stderr, "no commands found in file \"%s\"\n", argv[1]);
    return EXIT_FAILURE;
  }

  printf("; how to compile: nasm -f bin <input file with this code.asm> -o "
         "<output executable.com>\n\n"
         "org 0x100\n"
         "bits 16\n\n"
         "    mov     bx, data\n"
         "    mov     di, bx\n"
         "    mov     cx, 30000\n"
         "    xor     al, al\n"
         "    cld\n"
         "    rep     stosb\n\n"
         "    jmp     code\n\n"
         "print:\n"
         "    mov     ah, 2\n"
         "    cmp     byte [bx], 10\n"
         "    jne     lprint1\n"
         "    mov     dl, 13\n"
         "    int     0x21\n"
         "lprint1:\n"
         "    mov     dl, [bx]\n"
         "    int     0x21\n"
         "    ret\n\n"
#if 01
         // buffered input
         "input:\n"
         "    cmp     byte [kbdbuf+1], 0\n"
         "    jne     linput1\n"
         "    mov     ah, 0xa\n"
         "    mov     dx, kbdbuf\n"
         "    int     0x21\n"
         "    inc     byte [kbdbuf+1]\n"
         "linput1:\n"
         "    mov     al, [kbdbuf+2]\n"
         "    cmp     al, 13\n"
         "    jne     linput4\n"
         "    mov     al, 10\n"
         "linput4:\n"
         "    mov     [bx], al\n"
         "    mov     si, kbdbuf+3\n"
         "    mov     di, kbdbuf+2\n"
         "    xor     cx, cx\n"
         "    dec     byte [kbdbuf+1]\n"
         "    mov     cl, [kbdbuf+1]\n"
         "    jz      linput3\n"
         "linput2:\n"
         "    lodsb\n"
         "    stosb\n"
         "    loop    linput2\n"
         "linput3:\n"
         "    ret\n\n"
#else
         // unbuffered input
         "input:\n"
         "    mov     ah, 1\n"
         "    int     0x21\n"
         "    cmp     al, 13\n"
         "    jne     linput\n"
         "    mov     al, 10\n"
         "linput:\n"
         "    mov     [bx], al\n"
         "    ret\n\n"
#endif
         "code:\n\n");

  for (pc = &code[0]; pc < pcEnd; pc++)
  {
    switch (*pc)
    {
    case '>':
      printf("    inc     bx\n");
      break;
    case '<':
      printf("    dec     bx\n");
      break;
    case '+':
      printf("    inc     byte [bx]\n");
      break;
    case '-':
      printf("    dec     byte [bx]\n");
      break;
    case '.':
      printf("    call    print\n");
      break;
    case ',':
      printf("    call    input\n");
      break;
    case '[':
      printf("label%u:\n", (unsigned)(pc - &code[0]));
      printf("    cmp     byte [bx], 0\n");
      printf("    je      label%u\n", (unsigned)brMatch[pc - &code[0]]);
      break;
    case ']':
      printf("    jmp     label%u\n", brMatch[pc - &code[0]]);
      printf("label%u:\n", (unsigned)(pc - &code[0]));
      break;
    }
  }

  printf("\n    ret\n\n");
  printf("kbdbuf:\n"
         "    db      254\n"
         "    db      0\n"
         "    times   256 db 0\n\n");
  printf("data:\n");

  return EXIT_SUCCESS;
}

如果你喂它hello world程序:

++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.

它将生成可编译的汇编代码:

; how to compile: nasm -f bin <input file with this code.asm> -o <output executable.com>

org 0x100
bits 16

    mov     bx, data
    mov     di, bx
    mov     cx, 30000
    xor     al, al
    cld
    rep     stosb

    jmp     code

print:
    mov     ah, 2
    cmp     byte [bx], 10
    jne     lprint1
    mov     dl, 13
    int     0x21
lprint1:
    mov     dl, [bx]
    int     0x21
    ret

input:
    cmp     byte [kbdbuf+1], 0
    jne     linput1
    mov     ah, 0xa
    mov     dx, kbdbuf
    int     0x21
    inc     byte [kbdbuf+1]
linput1:
    mov     al, [kbdbuf+2]
    cmp     al, 13
    jne     linput4
    mov     al, 10
linput4:
    mov     [bx], al
    mov     si, kbdbuf+3
    mov     di, kbdbuf+2
    xor     cx, cx
    dec     byte [kbdbuf+1]
    mov     cl, [kbdbuf+1]
    jz      linput3
linput2:
    lodsb
    stosb
    loop    linput2
linput3:
    ret

code:

    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
label10:
    cmp     byte [bx], 0
    je      label41
    inc     bx
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     bx
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     bx
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     bx
    inc     byte [bx]
    dec     bx
    dec     bx
    dec     bx
    dec     bx
    dec     byte [bx]
    jmp     label10
label41:
    inc     bx
    inc     byte [bx]
    inc     byte [bx]
    call    print
    inc     bx
    inc     byte [bx]
    call    print
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    call    print
    call    print
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    call    print
    inc     bx
    inc     byte [bx]
    inc     byte [bx]
    call    print
    dec     bx
    dec     bx
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    call    print
    inc     bx
    call    print
    inc     byte [bx]
    inc     byte [bx]
    inc     byte [bx]
    call    print
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    call    print
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    dec     byte [bx]
    call    print
    inc     bx
    inc     byte [bx]
    call    print
    inc     bx
    call    print

    ret

kbdbuf:
    db      254
    db      0
    times   256 db 0

data:

如果你编译它,你将能够在DOS,Windows 9x / XP(可能是32位Vista / 7)和DosBox中运行它。

毫不奇怪,输出是:

Hello World!

UPDATE :上述代码中基于DOS的输入和输出例程可以通过直接访问屏幕缓冲区和键盘端口来替换。键盘代码还需要处理键盘中断。在x86 PC上做起来并不是很难。你真的可以实现一种语言的编译器,可以在没有操作系统的裸硬件上运行。

您还应该查看Forth,因为这正是给定环境的语言类型。它很容易实现。比C语言要容易得多,比大脑更容易,有点与装配相当。

更新2 :这是一个小型(大小约1KB)的brainfuck解释器,它没有使用任何DOS或BIOS功能:

; file: bfint.asm
; compile: nasm.exe -f bin bfint.asm -o bfint.com
; run in: DOS, DosBox or equivalent

bits 16
org 0x100

section .text

SCREEN_WIDTH   equ 80
SCREEN_HEIGHT  equ 25
SCAN_BUF_SIZE  equ 256

MAX_CODE_SIZE  equ 20000
MAX_DATA_SIZE  equ 30000

    cld

    ; set new keyboard (IRQ1) ISR
    push    byte 0
    pop     es
    cli                         ; update ISR address w/ ints disabled
    mov     word [es:9*4], Irq1Isr
    mov     [es:9*4+2], cs
    sti

    push    cs
    pop     es

Restart:

    call    ClearScreen
    mov     si, MsgHello
    call    PrintStr

    mov     word [CodeSize], 0
    mov     byte [EnterCount], 0

WaitForKey:
    call    GetKey

    ; Escape erases code
    cmp     ah, 1      ; Escape
    je      Restart

    ; Non-characters are ignored
    cmp     al, 0      ; non-character key
    je      WaitForKey

    ; Enter is "printed" but not stored, use for formatting
    cmp     al, 10     ; Enter
    je      KeyEnter
    mov     byte [EnterCount], 0

    ; Backspace deletes last character
    cmp     al, 8      ; Backspace
    je      KeyBackspace

    ; Space is printed but not stored, use for formatting
    cmp     al, " "    ; Space
    je      PrintOnly

    ; 0 runs a test program
    cmp     al, "0"
    je      TestProgram

    ; Other chracters are stored as code
    mov     bx, [CodeSize]
    cmp     bx, MAX_CODE_SIZE
    jae     ErrCodeTooBig
    mov     [Code + bx], al
    inc     word [CodeSize]
PrintOnly:
    call    PrintChar
    jmp     WaitForKey

ErrCodeTooBig:
    mov     si, MsgCodeTooBig
    call    PrintStr
    mov     word [CodeSize], 0
    jmp     WaitForKey

KeyEnter:
    call    PrintChar
    inc     byte [EnterCount]
    cmp     byte [EnterCount], 1
    je      WaitForKey
    mov     byte [EnterCount], 0
    call    Execute
    jmp     WaitForKey

KeyBackspace:
    call    PrintChar
    cmp     word [CodeSize], 0
    je      WaitForKey
    dec     word [CodeSize]
    jmp     WaitForKey

TestProgram:
    mov     si, TestCode
    mov     di, Code
    mov     cx, TestCodeEnd - TestCode
    mov     [CodeSize], cx
    rep     movsb
    call    Execute
    jmp     WaitForKey

Execute:
    mov     si, Code ; code start
    xor     bp, bp ; instruction index

    mov     di, Data ; data start
    mov     cx, MAX_DATA_SIZE
    xor     al, al
    rep     stosb
    sub     di, MAX_DATA_SIZE
    xor     bx, bx ; data index

ExecuteLoop:
    cmp     bp, [CodeSize]
    jae     ExecuteDone

    mov     al, [bp+si]
    cmp     al, ">"
    je      IncPtr
    cmp     al, "<"
    je      DecPtr
    cmp     al, "+"
    je      IncData
    cmp     al, "-"
    je      DecData
    cmp     al, "."
    je      PrintData
    cmp     al, ","
    je      InputData
    cmp     al, "["
    je      While
    cmp     al, "]"
    je      EndWhile

    mov     si, MsgInvalidChar
    call    PrintStr
    call    PrintChar
    mov     al, 10
    call    PrintChar
    jmp     ExecuteDone

IncPtr:
    inc     bx
    jmp     ExecuteContinue

DecPtr:
    dec     bx
    jmp     ExecuteContinue

IncData:
    inc     byte [bx+di]
    jmp     ExecuteContinue

DecData:
    dec     byte [bx+di]
    jmp     ExecuteContinue

PrintData:
    mov     al, [bx+di]
    call    PrintChar
    jmp     ExecuteContinue

InputData:
    call    GetKey
    or      al, al
    jz      InputData
    mov     [bx+di], al
    jmp     ExecuteContinue

While:
    cmp     byte [bx+di], 0
    jne     ExecuteContinue
    mov     ax, 1
    mov     dx, "[]"
    call    FindMatchingBracket
ExecuteContinue:
    inc     bp
    jmp     ExecuteLoop

EndWhile:
    mov     ax, -1
    mov     dx, "]["
    call    FindMatchingBracket
    jmp     ExecuteLoop

ExecuteDone:
    mov     word [CodeSize], 0
    mov     si, MsgCompleted
    jmp     PrintStr

FindMatchingBracket:
    xor     cx, cx
FindMatchingBracket1:
    cmp     byte [bp+si], dl
    jne     FindMatchingBracket2
    inc     cx
    jmp     FindMatchingBracket3
FindMatchingBracket2:
    cmp     byte [bp+si], dh
    jne     FindMatchingBracket3
    dec     cx
    jnz     FindMatchingBracket3
    ret
FindMatchingBracket3:
    add     bp, ax
    jmp     FindMatchingBracket1

; Inputs:
; AL = ASCII character code
PrintChar:
    ; assuming it's a color text mode (not monochrome or graphics)
    pusha
    push    es

    push    word 0xb800
    pop     es
    mov     bx, [CursorPos]

    cmp     al, 8
    je      PrintCharBackSpace

    cmp     al, 10
    je      PrintCharBackLF

    cmp     al, 13
    je      PrintCharBackCR

    mov     [es:bx], al
    call    AdvanceCursorPosition

    jmp     PrintCharDone

PrintCharBackSpace:
    ; move the cursor back and erase the last character
    or      bx, bx
    jz      PrintCharDone
    dec     bx
    dec     bx
    mov     word [es:bx], 0x0720
    jmp     PrintCharSetCursorPos

PrintCharBackLF:
    ; move the cursor to the beginning of the next line - '\n' behavior
    add     bx, SCREEN_WIDTH * 2
    cmp     bx, SCREEN_WIDTH * SCREEN_HEIGHT * 2
    jc      PrintCharBackCR
    sub     bx, SCREEN_WIDTH * 2
    call    ScrollUp

PrintCharBackCR:
    ; move the cursor to the beginning of the current line - '\r' behavior
    mov     ax, SCREEN_WIDTH * 2
    xchg    ax, bx
    xor     dx, dx
    div     bx
    mul     bx
    mov     bx, ax

PrintCharSetCursorPos:
    mov     [CursorPos], bx
    shr     bx, 1
    call    SetCursorPosition

PrintCharDone:
PopEsAllRet:
    pop     es
    popa
    ret

ClearScreen:
    ; assuming it's a color text mode (not monochrome or graphics)
    pusha
    push    es

    push    word 0xb800
    pop     es
    xor     di, di
    mov     cx, SCREEN_WIDTH * SCREEN_HEIGHT
    mov     ax, 0x0720 ; character = space, color = lightgray on black
    rep     stosw

    xor     bx, bx
    mov     [CursorPos], bx
    call    SetCursorPosition

    jmp     PopEsAllRet

ScrollUp:
    ; assuming it's a color text mode (not monochrome or graphics)
    pusha
    push    es
    push    ds

    push    word 0xb800
    pop     es
    push    es
    pop     ds
    mov     si, SCREEN_WIDTH * 2
    xor     di, di
    mov     cx, SCREEN_WIDTH * (SCREEN_HEIGHT - 1)
    rep     movsw

    mov     cx, SCREEN_WIDTH
    mov     ax, 0x0720 ; character = space, color = lightgray on black
    rep     stosw

    pop     ds
    jmp     PopEsAllRet

; Inputs:
; DS:SI = address of NUL-terminated ASCII string
PrintStr:
    pusha
PrintStr1:
    lodsb
    or      al, al
    jz      PrintStrDone
    call    PrintChar
    jmp     PrintStr1
PrintStrDone:
    popa
    ret

; Inputs:
; BX = Y * SCREEN_WIDTH + X
SetCursorPosition:
    ; assuming it's a color text mode (not monochrome or graphics)
    pusha

%if 0
    mov     dx, 0x3d4
    mov     al, 0x0f
    out     dx, al
    inc     dx
    mov     al, bl
    out     dx, al

    dec     dx
    mov     al, 0x0e
    out     dx, al
    inc     dx
    mov     al, bh
    out     dx, al
%else
    mov     dx, 0x3d4
    mov     al, 0x0f
    mov     ah, bl
    out     dx, ax

    dec     al
    mov     ah, bh
    out     dx, ax
%endif

    popa
    ret

AdvanceCursorPosition:
    ; assuming it's a color text mode (not monochrome or graphics)
    pusha

    mov     ax, [CursorPos]
    inc     ax
    inc     ax
    cmp     ax, SCREEN_WIDTH * SCREEN_HEIGHT * 2
    jc      AdvanceCursorPosition1

    sub     ax, SCREEN_WIDTH * 2
    call    ScrollUp

AdvanceCursorPosition1:
    mov     [CursorPos], ax
    shr     ax, 1
    xchg    ax, bx
    call    SetCursorPosition

    popa
    ret

; Outputs:
; AH = scan code
; AL = character
GetKey:
    push    bx
    push    si

GetKeyRepeat:
    mov     ax, [ScanWriteIdx]
    mov     si, [ScanReadIdx]
    sub     ax, si
    jz      GetKeyRepeat
    mov     bx, si
    mov     ax, [ScanBuf + bx + si]
    inc     si
    and     si, SCAN_BUF_SIZE - 1
    mov     [ScanReadIdx], si

    pop     si
    pop     bx
    ret

Irq1Isr:
    pusha
    push    ds

    push    cs
    pop     ds

    ; read keyboard scan code
    in      al, 0x60

    cmp     al, 0x2a ; Left Shift down
    jne     Irq1Isr1
    or      byte [Shift], 1
Irq1Isr1:
    cmp     al, 0x36 ; Right Shift down
    jne     Irq1Isr2
    or      byte [Shift], 2
Irq1Isr2:
    cmp     al, 0xaa ; Left Shift up
    jne     Irq1Isr3
    and     byte [Shift], ~1
Irq1Isr3:
    cmp     al, 0xb6 ; Right Shift up
    jne     Irq1Isr4
    and     byte [Shift], ~2
Irq1Isr4:

    test    al, 0x80
    jnz     Irq1IsrEois ; key released

    mov     ah, al
    cmp     al, 58
    jc      Irq1Isr5
    xor     al, al   ; don't translate non-character keys
    jmp     Irq1Isr7
Irq1Isr5:
    mov     bx, ScanToChar
    cmp     byte [Shift], 0
    je      Irq1Isr6
    add     bx, ScanToCharShift - ScanToChar
Irq1Isr6:
    xlatb

Irq1Isr7:
    mov     bx, [ScanWriteIdx]
    mov     di, bx
    mov     [ScanBuf + bx + di], ax
    inc     bx
    and     bx, SCAN_BUF_SIZE - 1
    mov     [ScanWriteIdx], bx

Irq1IsrEois:
%if 0
    ; send EOI to XT keyboard
    in      al, 0x61
    mov     ah, al
    or      al, 0x80
    out     0x61, al
    mov     al, ah
    out     0x61, al
%endif

    ; send EOI to master PIC
    mov     al, 0x20
    out     0x20, al

    pop     ds
    popa
    iret

ScanToChar:
    db      0 ; unused
    db      0 ; Escape
    db      "1234567890-="
    db      8 ; Backspace
    db      9 ; Tab
    db      "qwertyuiop[]"
    db      10 ; Enter
    db      0 ; Ctrl
    db      "asdfghjkl;'`"
    db      0 ; Left Shift
    db      "\zxcvbnm,./"
    db      0 ; Right Shift
    db      0 ; Print Screen
    db      0 ; Alt
    db      " " ; Space
ScanToCharShift:
    db      0 ; unused
    db      0 ; Escape
    db      "!@#$%^&*()_+"
    db      8 ; Backspace
    db      9 ; Tab
    db      "QWERTYUIOP{}"
    db      10 ; Enter
    db      0 ; Ctrl
    db      'ASDFGHJKL:"~'
    db      0 ; Left Shift
    db      "|ZXCVBNM<>?"
    db      0 ; Right Shift
    db      0 ; Print Screen
    db      0 ; Alt
    db      " " ; Space

MsgHello:
    db      "Brainfuck Interpreter", 10, 10
    db      "Press 0 to run test code OR", 10
    db      "Type your code.", 10
    db      "Use Esc to erase it all or Backspace to delete last character.", 10
    db      "Press Enter twice to run it.", 10, 10, 0

MsgCodeTooBig:
    db      10, "Code's too big", 10, 0

MsgCompleted:
    db      10, "Code's completed", 10, 0

MsgInvalidChar:
    db      10, "Invalid character: ", 0

Shift           db      0

CursorPos       dw      0

ScanReadIdx     dw      0
ScanWriteIdx    dw      0

EnterCount      db      0

CodeSize        dw      0

TestCode:
    ; Hello World!
    db "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."
    ; Squares of 0 through 100
;    db "++++[>+++++<-]>[<+++++>-]+<+[>[>+>+<<-]++>>[<<+>>-]>>>[-]++>[-]+>>>+[[-]++++++>>>]<<<[[<++++++++<++>>-]+<.<[>----<-]<]<<[>>>>>[>>>[-]+++++++++<[>-<-]+++++++++>[-[<->-]+[<<<]]<[>+<-]>]<<-]<<-]"
    ; ROT13
;    db "+[,+[-[>+>+<<-]>[<+>-]+>>++++++++[<-------->-]<-[<[-]>>>+[<+<+>>-]<[>+<-]<[<++>>>+[<+<->>-]<[>+<-]]>[<]<]>>[-]<<<[[-]<[>>+>+<<<-]>>[<<+>>-]>>++++++++[<-------->-]<->>++++[<++++++++>-]<-<[>>>+<<[>+>[-]<<-]>[<+>-]>[<<<<<+>>>>++++[<++++++++>-]>-]<<-<-]>[<<<<[-]>>>>[<<<<->>>>-]]<<++++[<<++++++++>>-]<<-[>>+>+<<<-]>>[<<+>>-]+>>+++++[<----->-]<-[<[-]>>>+[<+<->>-]<[>+<-]<[<++>>>+[<+<+>>-]<[>+<-]]>[<]<]>>[-]<<<[[-]<<[>>+>+<<<-]>>[<<+>>-]+>------------[<[-]>>>+[<+<->>-]<[>+<-]<[<++>>>+[<+<+>>-]<[>+<-]]>[<]<]>>[-]<<<<<------------->>[[-]+++++[<<+++++>>-]<<+>>]<[>++++[<<++++++++>>-]<-]>]<[-]++++++++[<++++++++>-]<+>]<.[-]+>>+<]>[[-]<]<]"
TestCodeEnd:

section .bss

ScanBuf:
    resw SCAN_BUF_SIZE

Code:
    resb MAX_CODE_SIZE

Data:
    resb MAX_DATA_SIZE

如果您想将DOS(作为托管环境)和NASM从图片中删除,欢迎您手动对上述汇编代码进行编码,从中制作可启动软盘并启动它。

答案 2 :(得分:0)

规范的编译器学习书是龙书,http://dragonbook.stanford.edu/

然而,它确实更多地指向......精致的语言。你可能不想谈论无上下文的解析等(虽然我推荐那本书,它是双加硬但真棒。)

考虑到这一点,你可能想要找到一个非常简单的语言的解释器或编译器 - 也许是Brainfuck本身,也许像Scheme实现更有用。阅读,分析,了解它的作用。实现编译器使用的低级库函数,调整其代码生成器以输出您想要定位的任何品牌的机器代码,然后就完成了。

答案 3 :(得分:0)

实际上,我也有类似的项目。你想要的是编写一个在裸硬件上运行的编译器(没有任何操作系统)。 编译器只是一个类似于其他所有程序的程序,除了它将像你的情况一样在裸硬件上运行。

您可以考虑为编译器使用引导加载程序(引导加载程序不是操作系统)。引导加载程序通常会将操作系统从磁盘加载到内存中,以便仅在加载编译器而不是操作系统时执行。

有许多免费和开源的引导加载程序(谷歌为他们)。选择一个适合您需求的,或者如果您像我一样好奇/好奇,您甚至可以自己编写。

选择引导加载程序(或编写引导加载程序)要求您了解目标系统的引导方式 - 通过BIOS(旧)或UEFI(新的。它是BIOS的替代品)。随着编程语言的成熟,您可以用新的编程语言编写自己的引导加载程序。

希望这有帮助