Hi all,
Is "sfr" a typedef or a #define? How is it declared?
I would like to create a "pfr type" to access memory mapped peripherals in the xdata memory and also be able to use the same syntax for accessing them as with ordinary SFRs.
For example: pfr myReg = 0x3FF0; myReg = newVal;
Thanks you, Georgios
"What does 'sfr' stand for?"
I checked in chapter 1 of the so-called "bible" for the 8051, and it uses the abbreviation "SFR" twice before saying what it stands for!
Chapter 1 - 80C51 Family Architecture: www.nxp.com/.../80C51_FAM_ARCH_1.pdf
In fact, "SFR" stands for Special-Function Register; these are the means of accessing the 8051's various peripherals - timers, UART, etc, etc...
"Is 'sfr' a typedef or a #define?" Neither - it is a new keyword, provided specifically by Keil as an extension to the standard 'C' programming language: http://www.keil.com/support/man/docs/c51/c51_extensions.htm
"How is it declared?"
Please read the manual: http://www.keil.com/support/man/docs/c51/c51_le_sfrs.htm
"I would like to create a 'pfr type' to access memory mapped peripherals in the xdata memory"
Take a look at the _at_ keyword extension, and the xdata memory-space qualifier: http://www.keil.com/support/man/docs/c51/c51_le_absvarloc.htm http://www.keil.com/support/man/docs/c51/c51_le_xdata.htm
For reference, here are the links to the other chapters of the so-called "bible":
Chapter 2 - 80C51 Family Programmer's Guide and Instruction Set: www.nxp.com/.../80C51_FAM_PROG_GUIDE_1.pdf
Chapter 3 - 80C51 Family Hardware Description: www.nxp.com/.../80C51_FAM_HARDWARE_1.pdf