Reentrant function whose arguments are located to absolute addr

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Read-Only Author Bryan Wang Posted 19-Jul-2004 14:10 GMT Toolset C51	Reentrant function whose arguments are located to absolute addr Bryan Wang I defined a reentrant function with 4 long arguments like this (excerpt from the lst) 21 unsigned long func0(unsigned long a, unsigned long b, unsigned long c, unsigned long d) large reentrant 22 { 23 1 printf("--- Now in func 0 Calling bank A\n"); 24 1 func5A(a,b,c,d); 25 1 printf("--- Calling bank B\n"); 26 1 func8B(d,c,b,a); 27 1 return a+b+c+d; 28 1 }

Read-Only Author Bryan Wang Posted 19-Jul-2004 14:14 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang And part of its translated form in assembly is ; FUNCTION _?func0 (BEGIN) ; SOURCE LINE # 21 0000 90FFFC MOV DPTR,#0FFFCH 0003 120000 E LCALL ?C?ADDXBP 0006 120000 E LCALL ?C?LSTXDATA ; SOURCE LINE # 23 0009 7BFF MOV R3,#0FFH 000B 7A00 R MOV R2,#HIGH ?SC_120 000D 7900 R MOV R1,#LOW ?SC_120 000F 120000 E LCALL _printf The first MOV is to get the argument values (?) from $FFFC, however it happens to be an "empty" address in my chip. How does it happen? I supposed the argument address are determined only when linking, rather than compiling.

Read-Only Author Jon Ward Posted 19-Jul-2004 14:25 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Jon Ward Did you setup the reentrant stack pointer in the startup code? http://www.keil.com/support/docs/671.htm Jon

Read-Only Author Bryan Wang Posted 19-Jul-2004 16:13 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang Thanks for answering. It works fine now.

Read-Only Author Bryan Wang Posted 20-Jul-2004 16:13 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang I found the answer in http://www.keil.com/support/docs/1431.htm. Thanks anyway :)

Read-Only Author Bryan Wang Posted 20-Jul-2004 15:12 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang Another problem arose. What is the stack pointer of the reentrant functions and how to set it in the program, in C or ASM?

Read-Only Author Bryan Wang Posted 20-Jul-2004 16:00 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang I found the ?C_XBP is the reentrant stack pointer. Is there any way to locate it to a fixed address? I mean, I want to fix it at, say, D:0x08, and nowhere else. Thanks!

Read-Only Author Bryan Wang Posted 20-Jul-2004 16:14 GMT Toolset C51	RE: Reentrant function whose arguments are located to absolute addr Bryan Wang I found the answer in http://www.keil.com/support/docs/1431.htm. Thanks anyway :)

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