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/*******************************************/ /*compiler Keil C51 v6.23*/ /*name：main*/ unsigned char xdata temp; unsigned char xdata *p; void func(void); void main(void) { unsigned char xdata i; while(1) { p = &temp; *p = 98; func(); i = *p; } } /******************************************/ /*-------------------------------------- compile following program to assembly program, then link with the main function.ERROR!!! Why and how to chang the assembly program.please help me,thank you.! ------------------------------------------*/ #pragma src(MYPTR.A51) small extern unsigned char xdata *p; void func(void) { *p = 0xdd; } my E-mail:inspra@xjgroup.com name:huangjian
Read the section on pointers in the C51 manual - this tells you how pointer values are actually represented in memory. Then all you need to do is write your assembler accordingly to use those values!
What error? Jon
P is sbit in the PSW register. Use another name other than p.
using a single-character name like 'p' is not a good idea for a global variable! The AX51 & A251 assemblers have a CASE control to make them case-sensitive; otherwise, they are not. I couldn't find it actually stated in the manual, but I assume that A51 must be case-insensitive?
Yes,you are right.Thank you very much! But when I chang memory model from SMALL to LARGE or COMPACT,the program fly away.Please tell me why and how to adjust it.
"the program fly away" What does that mean?
It appears that your C program which you use SRC with is ALWAYS compiled in SMALL memory model. The following line:
#pragma src(MYPTR.A51) small