Please do not say 'paging' I can not handle the overhead for all the other stuff that fit nicely within 64k. I have a 2Mbyte flash that occasionally is accessed and the time here is not critical (the system pauses) as opposed to other processes that use only RAM. Is there an elegant way to access structures in that 24 bit address space or does it have to be bent folded and mutilated to access? Currently all addresses are specified with an 8 bit 'page' and a 16 bit 'address' and processed as such. I could gain some readability by having the whole in a long. Also this method require data to be stored so no structure cross a page boundary and that limitation is a nuisance. Erik
We are aware of the 16-bit offset limitation. This is why the compiler does not let you define objects that cross a 64KB boundary. AppNote 160 shows ways to solve this problem. Take a look to: http://www.keil.com/appnotes/docs/apnt_160.asp. See "EXPAND VARIABLE SPACE".
I tried the AN160 suggestion, there is no difference. In the case of actually using a MX chip and CX51, this would be a gross error.
C51 XMACtemq = (ReadPagedFlashC ((U32) (GPtsd + TSDflags), GC_TXI_pg) & OCU_TEXT_MASK); 001E E500 E MOV A,GPtsd+01H 0020 2401 ADD A,#01H 0022 FF MOV R7,A 0023 E500 E MOV A,GPtsd 0025 3400 ADDC A,#00H 0027 FE MOV R6,A 0028 E4 CLR A 0029 FC MOV R4,A 002A FD MOV R5,A 002B AD00 E MOV R5,GC_TXI_pg 002D 120000 E LCALL _ReadPagedFlashC C51 XMACtemq = (ReadPagedFlashC ((U16) (GPtsd + TSDflags), GC_TXI_pg) & OCU_TEXT_MASK); 001E E500 E MOV A,GPtsd+01H 0020 2401 ADD A,#01H 0022 FF MOV R7,A 0023 E500 E MOV A,GPtsd 0025 3400 ADDC A,#00H 0027 FE MOV R6,A 0028 AD00 E MOV R5,GC_TXI_pg 002A 120000 E LCALL _ReadPagedFlashC CX51 XMACtemq = (ReadPagedFlashC ((U16) (GPtsd + TSDflags), GC_TXI_pg) & OCU_TEXT_MASK); 001E E500 E MOV A,GPtsd+01H 0020 2401 ADD A,#01H 0022 FF MOV R7,A 0023 E500 E MOV A,GPtsd 0025 3400 ADDC A,#00H 0027 FE MOV R6,A 0028 AD00 E MOV R5,GC_TXI_pg 002A 120000 E LCALL _ReadPagedFlashC CX51 XMACtemq = (ReadPagedFlashC ((U32) (GPtsd + TSDflags), GC_TXI_pg) & OCU_TEXT_MASK); 001E E500 E MOV A,GPtsd+01H 0020 2401 ADD A,#01H 0022 FF MOV R7,A 0023 E500 E MOV A,GPtsd 0025 3400 ADDC A,#00H 0027 FE MOV R6,A 0028 E4 CLR A 0029 FC MOV R4,A 002A FD MOV R5,A 002B AD00 E MOV R5,GC_TXI_pg 002D 120000 E LCALL _ReadPagedFlashC
Instead of: U32 address = &MyStruct.MyField; what about: U32 address = (U32)&MyStruct + offsetof(MyStruct, MyField)
fine, but when it is structure within array fo structures within a structure and so on it becomes very unreadable. Erik Anyhow, with CX51 it should work, bcause there you can address 8Mbyte linearily.