📄 l51_bank.a51
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$NOMOD51 NOLINES
$NOCOND
;------------------------------------------------------------------------------
; This file is part of the BL51 / LX51 Banked Linker/Locater package
; Copyright (c) 1988 - 2001 Keil Elektronik GmbH and Keil Software, Inc.
; Version 2.21 (Code and Variable Banking for Classic 8051 Derivatives)
;------------------------------------------------------------------------------
;************************ Configuration Section *******************************
?B_NBANKS EQU 4 ; Define maximum Number of Banks *
; ; following values are allowed: 2, 4, 8, 16, 32, 64 *
; ; for BL51 the maximum value for ?B_BANKS is 32 *
; ; for LX51 the maximum value for ?B_BANKS is 64 *
; *
?B_MODE EQU 4 ; 4 for user-provided bank switch code *
;?B_MODE EQU 1 ; 0 for Bank-Switching via 8051 Port *
; ; 1 for Bank-Switching via XDATA Port *
; ; 4 for user-provided bank switch code *
; *
?B_RTX EQU 0 ; 0 for applications without real-time OS *
; ; 1 for applications using the RTX-51 real-time OS *
; *
?B_VAR_BANKING EQU 0 ; Variable Banking via L51_BANK (far memory support)*
; ; 0 Variable Banking does not use L51_BANK.A51 *
; ; 1 Variable Banking uses this L51_BANK.A51 module *
; Notes: ?B_VAR_BANKING uses the 'far' and 'far const' C51 memory types to *
; extent the space for variables in RAM and/or ROM of classic 8051 *
; device. The same hardware as for code banking is used. Program *
; code banking and variable banking share the same hardware I/O pins. *
; The C51 Compiler must be used with the VARBANKING directive. *
; Variable Banking is only supported with the LX51 linker/locater. *
; *
;?B_RST_BANK EQU 0xFF ; specifies the active code bank number after CPU *
?B_RST_BANK EQU 0x00 ; specifies the active code bank number after CPU *
; ; Reset. Used to reduce the entries in the *
; ; INTERBANK CALL TABLE. The value 0xFF disables *
; ; this LX51 linker/locater optimization. *
; Note: Interbank Call Table optimization is only possible with LX51. *
; *
;-----------------------------------------------------------------------------*
; *
IF ?B_MODE = 4; *
;-----------------------------------------------------------------------------*
; if ?BANK?MODE is 4 define the following switch macros *
; For bank switching via user-provided bank switch code you must define for *
; each memory bank a own macro which contains the bank switch code. The *
; following example shows how to use the I/O lines P1.4 and P1.7 for bank *
; switching. Since you can select just 4 banks with two address lines, just *
; four macros are defined. The number of macros must conform with the number *
; ?B_NBANKS number, i.e. for an application with 16 memory banks you must *
; define 16 macros. *
; *
; IMPORTANT NOTES: *
; 1. The bank switch logic must be initialized before using it. Therefore *
; add the following lines of code at the end of the STARTUP.A51 file: *
; : *
; EXTRN CODE (?B_SWITCH0) *
; CALL ?B_SWITCH0 ; init bank mechanism to code bank 0 *
; LJMP ?C_START ; line already exits at the end of file *
; : *
; *
; 2. If the bank switch macros and the additional control code generate more *
; than 256 bytes, you need to set the LONG_MACRO flag below. The error *
; message "BANK SWITCH CODE BIGGER THAN 256 BYTES, SET LONG_MACRO TO 1" *
; is generated in case that this is required. *
; *
; 3. The only registers that can be modified in this routines without prior *
; saving are: DPTR and ACC. *
; *
; *
LONG_MACRO EQU 0 ; 0 default, for normal macros and up to 8 banks *
; ; 1 big macro code or many banks *
; *
; *
BANKREG DATA 9AH ; Memory Bank select Function Register
;P1 DATA 90H ; I/O Port Addresses *
;P3 DATA 0B0H ; *
; *
SWITCH0 MACRO ; Switch to Memory Bank #0 *
MOV BANKREG, #0H
; CLR P1.5 ; Clear Port 1 Bit 5 *
; CLR P3.3 ; Clear Port 3 Bit 3 *
ENDM ; *
; *
SWITCH1 MACRO ; Switch to Memory Bank #1 *
MOV BANKREG, #1H
; SETB P1.5 ; Set Port 1 Bit 5 *
; CLR P3.3 ; Clear Port 3 Bit 3 *
ENDM ; *
; *
SWITCH2 MACRO ; Switch to Memory Bank #2 *
MOV BANKREG, #2H
; CLR P1.5 ; Clear Port 1 Bit 5 *
; SETB P3.3 ; Set Port 3 Bit 3 *
ENDM ; *
; *
SWITCH3 MACRO ; Switch to Memory Bank #3 *
MOV BANKREG, #3H
; SETB P1.5 ; Set Port 1 Bit 5 *
; SETB P3.3 ; Set Port 3 Bit 3 *
ENDM ; *
; *
;-----------------------------------------------------------------------------*
ENDIF; *
; *
; *
;******************************************************************************
; *
; THEORY OF OPERATION *
; ------------------- *
; The section below describes the code generated by BL51 or LX51 and the *
; operation of the L51_BANK.A51 module. BL51/LX51 generates for each *
; function that is located in a code memory bank and called from the common *
; area or a different code bank and entry into the INTRABANK CALL TABLE. The *
; INTRABANK CALL TABLE is located in the SEGMENT ?BANK?SELECT and listed in *
; the Linker MAP file. The entries in that TABLE have the following format: *
; *
; ?FCT?1: MOV DPTR,#FCT ; Load Address of target FCT *
; JMP ?B_BANKn ; Switch to Bank and Jump to Target Code *
; *
; Instead of directly calling the function FCT, the Linker changes the entry *
; to ?FCT?1. This entry selects the bank where the function FCT is located *
; and calls that function via the routines defined in this L51_BANK.A51 file. *
; The L51_BANK.A51 file contains two sets of functions for each bank: *
; *
; ?B_BANKn is a routine which saves the entry of the ?B_SWITCHn function *
; for the current active bank on the STACK and switches to the *
; bank 'n'. Then it jumps to the address specified by the DPTR *
; register. It is allowed to modify the following registers in *
; the ?B_BANKn routine: A, B, R0, DPTR, PSW *
; *
; ?B_SWITCHn is a function which selects the bank 'n'. This function is *
; used at the end of a user function to return to the calling *
; code bank. Only the following registers may be altered in the *
; ?B_SWITCHn function: R0, DPTR *
; *
; The current active bank is stored in ?B_CURRENTBANK. RTX-51 uses this *
; variable to restore the code bank after a task switch. To get correct *
; results, ?B_CURRENTBANK must be set to the code bank before the hardware *
; switch is done, or the code banking sequences must be interrupt protected. *
;******************************************************************************
NAME ?BANK?SWITCHING
PUBLIC ?B_NBANKS, ?B_MODE, ?B_CURRENTBANK, ?B_MASK
PUBLIC ?B_FACTOR, ?B_RST_BANK
; Standard SFR Symbols required in L51_BANK.A51
ACC DATA 0E0H
B DATA 0F0H
DPL DATA 82H
DPH DATA 83H
IE DATA 0A8H
EA BIT IE.7
; generate Mask and Bank Number Information
IF ?B_NBANKS <= 2
MASK EQU 00000001B
ELSEIF ?B_NBANKS <= 4
MASK EQU 00000011B
ELSEIF ?B_NBANKS <= 8
MASK EQU 00000111B
ELSEIF ?B_NBANKS <= 16
MASK EQU 00001111B
ELSEIF ?B_NBANKS <= 32
MASK EQU 00011111B
ELSE
MASK EQU 00111111B
ENDIF
IF ?B_MODE = 4 ;**************************************************************
?B_FACTOR EQU 0 ; Dummy Declarations
?B_FIRSTBIT EQU 0
?B_MASK EQU MASK
?BANK?SELECT SEGMENT CODE
?BANK?DATA SEGMENT DATA
RSEG ?BANK?DATA
?B_CURRENTBANK: DS 1
BANK MACRO N
PUBLIC ?B_BANK&N
?B_BANK&N:
PUSH ?B_CURRENTBANK
MOV A,#HIGH ?BANK?SWITCH
PUSH ACC
PUSH DPL
PUSH DPH
ENDM
SWITCH MACRO N
PUBLIC ?B_SWITCH&N
IF (LONG_MACRO = 1)
?B_SWITCHJ&N:
ELSE
?B_SWITCH&N:
ENDIF
MOV ?B_CURRENTBANK,#LOW ?B_SWITCH&N
SWITCH&N
RET
ENDM
IF (LONG_MACRO = 1)
SWITCHJ MACRO N
?B_SWITCH&N:
JMP ?B_SWITCHJ&N
ENDM
ENDIF
?BANK?SWITCH SEGMENT CODE PAGE
RSEG ?BANK?SWITCH
B_SWITCH_START EQU $
IF (LONG_MACRO = 1)
; Generate ?B_SWITCHn jmp table entries
CNT SET 0
REPT ?B_NBANKS
SWITCHJ %CNT
CNT SET CNT+1
ENDM
ENDIF
; Generate ?B_SWITCHn functions
CNT SET 0
REPT ?B_NBANKS
BANK %CNT
SWITCH %CNT
CNT SET CNT+1
ENDM
B_SWITCH_SIZE EQU $-B_SWITCH_START
IF (LONG_MACRO = 0) AND (B_SWITCH_SIZE > 256)
__ERROR__ "BANK SWITCH CODE BIGGER THAN 256 BYTES, SET LONG_MACRO TO 1"
ENDIF
ENDIF ; close block IF ?B_MODE = 4 *******************************************
RSEG ?BANK?SELECT
;************************ SWITCHBANK FUNCTION *******************************
; *
; SWITCHBANK allows use of bank-switching for C programs *
; *
; prototype: extern switchbank (unsigned char bank_number); *
; *
;******************************************************************************
PUBLIC _SWITCHBANK, ?B_SWITCHBANK_A
_SWITCHBANK: MOV A,R7
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