如何在ARM程序集中聲明一個定義並使用它？

Question

我試圖用icachetest工作，它有一個文件，任命icache.s包含：

#define LOOP \ 
     subs r2, r2, #1    ; \ 
     mov  r0, r0     ; \ 
     mov  r0, r0     ; \ 
     mov  r0, r0     ; \ 
     mov  r0, r0     ; \ 
     mov  r0, r0     ; \ 
     beq  end_loop    ; \ 
     mov  r0, r0     ; \ 

我使用arm-eabi-as編譯這個項目，但我得到這個錯誤：

AS  icache.S 
icache.S: Assembler messages: 
icache.S:16: Error: junk at end of line, first unrecognized character is `\' 
icache.S:17: Error: junk at end of line, first unrecognized character is `\' 
icache.S:18: Error: junk at end of line, first unrecognized character is `\' 
icache.S:19: Error: junk at end of line, first unrecognized character is `\' 
icache.S:20: Error: junk at end of line, first unrecognized character is `\' 
icache.S:21: Error: junk at end of line, first unrecognized character is `\' 
icache.S:22: Error: junk at end of line, first unrecognized character is `\' 
icache.S:23: Error: junk at end of line, first unrecognized character is `\' 
icache.S:52: Error: bad instruction `loop LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP' 
icache.S:53: Error: bad instruction `loop LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP' 
icache.S:54: Error: bad instruction `loop LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP LOOP' 

Answer 1

的LOOP是其他人指出的宏。由於它沒有參數或條件，因此很容易用gas宏代替。

.macro LOOP 
    subs r2, r2, #1 
    mov  r0, r0 
    mov  r0, r0 
    mov  r0, r0 
    mov  r0, r0 
    mov  r0, r0 
    beq  end_loop 
    mov  r0, r0 
.endm 

它會表現一樣在此之後一個#define，與只有一個是每行允許的警告。 ARM彙編程序確實允許多行操作碼（據我所知）。

您可以使用.rept重複該宏。

.rept 2048 
    LOOP 
.endr