This is file "sections.asm".
; I found the following message in Microchip's support site. The URL is: ; http://support2.microchip.com/KBSearch/KB_Ticket.aspx?ID=Tt6UJ9A0003LM ; ; Unfortunately these pseudo-instructions don't work as inline assembly, ; so I had to make this separate .asm module. ; The functions are used inside 'port.c' and are called by 'pxPortInitialiseStack' ; (GetTMPDATALen, GetTMPDATAStrt, GetMATHDATALen, GetMATHDATAStrt) and ; by the macros 'portSAVE_CONTEXT' (SaveTMP_MATH) and 'portRESTORE_CONTEXT' ; (RestoreTMP_MATH'). ;------------------------------------------------------------------------------- ; Start of the message: ;------------------------------------------------------------------------------- ; ; Issue ; ; I'm developping a RTOS for the PIC18F258 using MPLAB-C18. I need to save in the ; task context the "MATH_DATA" and ".tmpdata" sections. But their address and size ; are only known after linking. The question is: How can I know the address and ; size of both sections at run time? ; ; Thanks ; ; Solution ; You CAN get the section location and size at runtime using MPASM. ; There are a few undocumented operators and pseudo-instructions. ; ; The SCNSZ operators give you the size of the section. ; The SCNSTART operators give you the starting address of a section. ; The SCNEND operators give you the ending address of a section. ; The SCNSTART_LFSR pseudo-instruction gives you an LFSR instruction with the starting address of the section. ; The SCNEND_LFSR pseudo-instruction gives you an LFSR instruction with the ending address of the section. ; ; Example: ; CODE ; movlw SCNSZ_LOW .tmpdata ; movlw SCNSZ_HIGH .tmpdata ; movlw SCNSZ_UPPER .tmpdata ; movlw SCNSTART_LOW .tmpdata ; movlw SCNSTART_HIGH .tmpdata ; movlw SCNSTART_UPPER .tmpdata ; movlw SCNEND_LOW .tmpdata ; movlw SCNEND_HIGH .tmpdata ; movlw SCNEND_UPPER .tmpdata ; ; SCNSTART_LFSR 0, .tmpdata ; SCNEND_LFSR 0, .tmpdata ; ; END ; ; These operators and pseudo-instructions will be documented in the next revision ; of the MPASM User's Guide. ; ;------------------------------------------------------------------------------- ; End of the message ;------------------------------------------------------------------------------- ;=============================================================================== ; Copyright (c) 2007-2008, Isaac Marino Bavaresco ; All rights reserved. ; ; Redistribution and use in source and binary forms, with or without ; modification, are permitted provided that the following conditions are met: ; * Redistributions of source code must retain the above copyright ; notice, this list of conditions and the following disclaimer. ; * Neither the name of the author nor the ; names of its contributors may be used to endorse or promote products ; derived from this software without specific prior written permission. ; ; THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''AS IS'' AND ANY ; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED ; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE ; DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY ; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; ; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;=============================================================================== ; isaacbavaresco@yahoo.com.br ;=============================================================================== #include <P18CXXX.INC> ;=============================================================================== radix decimal ;=============================================================================== code ;=============================================================================== global GetTMPDATAStrt GetTMPDATAStrt: movlw SCNSTART_LOW .tmpdata movwf PRODL movlw SCNSTART_HIGH .tmpdata movwf PRODH return 0 ;=============================================================================== global GetTMPDATALen GetTMPDATALen: movlw SCNSZ_LOW .tmpdata return 0 ;=============================================================================== global GetMATHDATAStrt GetMATHDATAStrt:movlw SCNSTART_LOW MATH_DATA movwf PRODL movlw SCNSTART_HIGH MATH_DATA movwf PRODH return 0 ;=============================================================================== global GetMATHDATALen GetMATHDATALen: movlw SCNSZ_LOW MATH_DATA return 0 ;=============================================================================== global SaveTMP_MATH SaveTMP_MATH: SCNSTART_LFSR 0, .tmpdata movlw SCNSZ_LOW .tmpdata SaveLoop1: movff POSTINC0,PREINC1 addlw -1 bnz SaveLoop1 SCNSTART_LFSR 0, MATH_DATA movlw SCNSZ_LOW MATH_DATA SaveLoop2: movff POSTINC0,PREINC1 addlw -1 bnz SaveLoop2 return 0 ;=============================================================================== global RestoreTMP_MATH RestoreTMP_MATH: SCNEND_LFSR 0, MATH_DATA movlw SCNSZ_LOW MATH_DATA RestoreLoop1: movff POSTDEC1,POSTDEC0 addlw -1 bnz RestoreLoop1 SCNEND_LFSR 0, .tmpdata movlw SCNSZ_LOW .tmpdata RestoreLoop2: movff POSTDEC1,POSTDEC0 addlw -1 bnz RestoreLoop2 return 0 ;=============================================================================== end ;===============================================================================