LPC23XX的程序移植

关于LPC24XX的程序移植近来单片机升级了，一下子进入32位时代，有点措手不及！还好，网络互相的现代，工程师不必从头开始，充分利用网络资源，加快开发进程。

由于以前一直使用KEIL开发51单片机，使用方便，便于调试仿真。

值得庆幸的是现在ARM型单片机也可以在KEIL中调试。

可是网上大部分ARM实例是基于ADS的。

直接移植过来就会一警告和错误。

为了加快开发进程，还是选择移植借鉴部分实用例程。

具体解决问题方法如下：新推出的KEIL版开发工具RVMDK与老版ADS在工具架构组成上有以下不同：ARM编译器版本、调试器、软件仿真、以及调试单元。

出现如下提示：USBdma.h(128): warning: #1-D: last line of file ends without a newline compiling USBDriver.c...USBHAL.h(40): warning: #1-D: last line of file ends without a newline USBdma.h(128): warning: #1-D: last line of file ends without a newline提示："文件结束了但没有空行"这个警告, 这是由RVMDK编译器产生的警告，所有程序文件最后一行必须有空行，也可不去理它。

在提示处按一下回车就行了。

Startup.s(214): warning: A1608W: MOV pc,<rn> instruction used, but BX <rn> is preferredStartup.s(258): warning: A1608W: MOV pc,<rn> instruction used, but BX <rn> is preferred由于编译器版本的变化，对应的编译选项也有所变化。

将options for target中asm标签页里面的Eenable ARM/Thumb interworking复选框去掉，就不产生这样的告警信息啦，不过不知道这样做会影响什么！也可以根据提示改为BX跳转。

如果您的程序中存在ARM/Thumb指令相互调用的情况，那么使用BX指令能够返回到正确的处理器状态。

而使用MOV指令则不能实现处理器状态的切换。

所以keil编译器建议您使用BX指令。

例如把MOV PC, LR 改为BX LR 。

fio_release.axf: Error: L6238E: startup.o(vectors) contains invalid call from '~PRES8' function to 'REQ8' function FIQ_E xception.fio_release.axf: Error: L6238E: startup.o(vectors) contains invalid call from '~PRES8' function to 'REQ8' function Targe tResetInit.这是由于对目标文件进行链接时，ARM工具的连接器会严格检查各个文件（objects），判断它们是否复合ARM体系结构的ABI表准。

由于RVCT与ADS编译链接工具所遵循的ARM ABI不同，所以将ADS 的遗留工程直接移植到RVMDK并进行连接时，用户可能会遇到错误或者警告：新工具的ABI要求在函数调用时，系统必须保证堆栈指针8byte 对齐，即每次进栈或者出栈的寄存器数目必须为偶数。

这是为了能够更加高效的使用STM与LDR指令对“double”或者“long long”类型的数据进行访问。

而老的ARM开发工具ADS并没有考虑到新的ARM内核架构，其ABI对于堆栈的操作仅仅要求4byte对齐。

所以当用户将在ADS中编译连接成功的工程代码移植到RVMDK上，或者将老的、ADS遗留的目标文件、库文件在新工具RVMDK中进行连接时，RVMDK的连接器就会报出以上的错误。

解决方法如下：在每个汇编文件的开头，添加“PRESERVE8”指令。

AREA vectors,CODE,READONLY之前加PRESERVE8。

如下：AREA vectors,CODE,READONLY改为：PRESERVE8AREA vectors,CODE,READONLY检查汇编源码中的指令，确保堆栈操作指令是8byte对其的。

ADS的遗留代码一次性将5个寄存器压栈，由于ARM的指令寄存器宽度为32位，即4byte，显然5个寄存器入栈之后，堆栈指针不能够满足64位，8byte对齐。

为了解决这种情况，我们可以将另外一个并不需要压栈的寄存器，R12，同时压栈，这样当6个32位寄存器进栈之后，堆栈就能满足64位对齐了。

如：STMFD SP!, {R0-R3, LR}改为：STMFD SP!, {R0-R3, R12,LR} 好了通过以简单的更改，程序通过了。

由于接触时间太短，分享的只是解决方法，详细部分还不太清楚。

希望共同讨论！Linker Error: L6238E: foo.o(.text) contains invalid call from'~PRES8' function to 'REQ8'默认分类2008-07-11 14:42:21 阅读86 评论0 字号：大中小订阅Linker Error: L6238E: foo.o(.text) contains invalid call from '~PRES8' function to 'REQ8'function foobarApplies to: Assembler, Linker, RealView Developer Kit (RVDK) for OKI , RealView Developer Suite (RVDS) 2.0, RealView Developer Suite (RVDS) 2.1, RealView Developer Suite (RVDS) 2.2, RealView Development Suite (RVDS) 3.0, RealView Development Suite (RVDS) 3.1This RVDS/RVCT linker error is given where a stack alignment conflict is detected in object code. The "ABI for the ARM Architecture" demands that code maintains 8-byte stack alignment at its interfaces. This allows efficient use of LDRD and STRD instructions (in ARM Architecture 5TE and later) to access 8-byte-aligned "double" and "long long" data types.Symbols like '~PRES8' and 'REQ8' are "Build Attributes" of the objects.∙PRES8 means the object PREServes 8-byte alignment of the stack.∙~PRES8 means the object does NOT preserve 8-byte alignment of the stack (~ meaning NOT).∙REQ8 means the object REQuires 8-byte alignment of the stack.This link error typically occurs in two cases:∙where assembler code (that does not preserve 8-byte stack alignment) calls compiled C/C++ code (that requires 8-byte stack alignment), and∙when attempting to link legacy SDT/ADS objects with RVCT 2.x objects. Legacy SDT/ADS objects that do not have these attributes are treated as '~PRES8', even if they doactually happen to preserve 8-byte alignment.For example:Error: L6238E: foo.o(.text) contains invalid call from '~PRES8' function to 'REQ8' function foobarThis means that there is a function in the object foo.o (in the section named .text) that does not preserve 8-byte stack alignment, but which is trying to call function foobar that requires 8-byte stack alignment.A similar warning that may be encountered, where the address of an external symbol is being referred to, is:Warning: L6306W: '~PRES8' section foo.o(.text) should not use the address of 'REQ8' function foobarSolutionsThere are two possible approaches to dealing with this issue:1) If you have access to all your source code and are allowed to rebuild itIn this case you should rebuild all your objects/libraries using the latest version of the compilation tools. Note that if you have any assembler files, you will need to:i) check that all instructions preserve 8-byte stack alignment, and if necessary, correct them.e.g. change:STMFD sp!, {r0-r3, lr} ; push an odd number of registersto:STMFD sp!, {r0-r3, r12, lr} ; push an even number of registersand:ii) add the PRESERVE8 directive to the top of each assembler file.e.g. change:AREA Init, CODE, READONLYto:PRESERVE8AREA Init, CODE, READONLY(the PRES8 attribute applies to the whole object, not just the code section).2) If you cannot rebuild all of your source codeIf you have any legacy objects/libraries that cannot be rebuilt, either because you do not have the source code, or because the old objects must not be rebuilt (e.g. for qualification/certification reasons), then you must inspect the legacy objects to check whether they preserve 8-byte alignment or not. Use "fromelf -c" to disassemble the object code. C/C++ code compiled with ADS 1.1 or later will normally preserve 8-byte alignment, but assembled code will not.If your objects do indeed preserve 8-byte alignment, then the linker error L6238E can be suppressed with the use of "--diag_suppress 6238" on the linker command line. By using this, you are effectively saying "I guarantee that these objects are PRES8". The linker warning L6306W is suppressible with "--diag_suppress 6306".If you are linking with legacy objects/libraries then you should also read the information on the option "--apcs /adsabi" in the FAQ entry "Are legacy ADS objects/libraries compatible with RVCT 2.0 ?".。