KEIL C51環境下，彙編與C語言交叉編譯的問題

文章目錄

• QUESTION
• ANSWER
• MORE INFORMATION
• SEE ALSO
• FORUM THREADS

1. 關於如何在C語言中嵌入彙編命令：

轉載自：http://www.keil.com/support/docs/2308.htm

C51: GETTING INLINE ASSEMBLY TO WORK

Information in this article applies to:

• C51 All Versions

QUESTION

How do I implement inline assembly in C51 using the ASM and
ENDASM directives. I have read some of the knowledgebase articles relating to this problem, but I still cannot get it to work.

ANSWER

The following example program, MAIN.C, demonstrates some simple inline assembly.

void main(void){   test();#pragma asm      JMP   $           ; endless loop#pragma endasm}

The following rules apply to C51 inline assembly:

• To use #pragma ASM/ENDASM, you must set the Generate Assembler SRC File andAssemble SRC File source file compile options in µVision by right-clicking your source file name in the Project Workspace and selectingOptions
  for File.
• When using the Generate Assembler SRC File and Assemble SRC File options in µVision, if there are no other C modules in your project, you must manually include the C51 Run-Time Library (C51S.LIB, C51M.LIB, or C51L.LIB).

MORE INFORMATION

• Refer to ASM in the Cx51 User's Guide.
• Refer to Interfacing C to Assembler in the Cx51 User's Guide.

SEE ALSO

• C51: PROBLEMS WITH #PRAGMA ASM
• GENERAL: SRC DIRECTIVE
• BL51: WARNING L1 (UNRESOLVED EXTERNAL) USING INLINE ASSEMBLY
• C51: INLINE ASSEMBLY GENERATES TARGET OUT OF RANGE
• C51: IN-LINE ASM GIVES COMPILER WARNINGS

FORUM THREADS

The following Discussion Forum threads may provide information related to this topic.

• Asembly code in C

Last Reviewed: Thursday, July 17, 2008

--轉載自：http://blog.21ic.com/user1/6088/archives/2010/68469.html

方法：（假設當前工程中只有一個C代碼檔案）

       第1步：建立一個工程，添加C檔案，編譯通過

       第2步：右擊Keil介面中Project Workspace裡的C檔案名稱，選擇‘Option
for…’

       第3步：點擊‘Generate Assembler SRC File’‘Assemble
SRC File’兩個三態複選框使它們呈高亮並勾選，點擊確定

       第4步：將KEIL安裝目錄下C51/LIB/C51S.LIB（如果是SMALL模式）檔案複製到工程目錄下

       第5步：添加庫檔案C51S.LIB檔案到工程，即右擊‘Source
Group 1’，選擇‘Add Files to Group …’，在工程目錄下選擇C51S.LIB，點擊開啟

       （因為有了第3步中的操作，如果在這裡不添加庫檔案，則編譯產生的HEX檔案不能被單片機正確執行，同時編譯時間會出現一個警告：

WARNING L1:UNRESOLVED EXTERNAL SYMBOL

SYMBOL:  ?C_STARTUP

無法識別?C_STARTUP這個標號，這個標號是在庫檔案中定義

）

       第6步：開啟工程目錄，可以看到新產生一個副檔名為.SRC的檔案，將其副檔名改成.A51

       第7步：添加這個.A51檔案到工程（這時候工程就包含C51S.LIB庫檔案，不然編譯會產生第5步中說明的警告，且產生的HEX檔案不能被單片機正確運行）

       第8步：重新編譯，產生HEX檔案，載入到單片機中，可以發現與C語言啟動並執行現象是一致的