📄 os_cpu_a._s
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;*******************************************************************************
; uC/OS-II
; The Real-Time Kernel
;
; AT90 Specific code
; (ICC V6.21)
;
;
; File: OS_CPU_A.S
; By:
; Modified by:
; Port Version: V1.00
;
;
;*******************************************************************************
;include
;*******************************************************************************
; I/O PORT ADDRESSES
;*******************************************************************************
SREG =0x3F
SPH =0x3E
SPL =0x3D
TCNT0 =0x32
PIND = 0x10
PORTD = 0x12
;*******************************************************************************
; MACROS
;*******************************************************************************
; Push registers
.macro PUSHRS
ST -Y,R0
ST -Y,R1
ST -Y,R2
ST -Y,R3
ST -Y,R4
ST -Y,R5
ST -Y,R6
ST -Y,R7
ST -Y,R8
ST -Y,R9
ST -Y,R10
ST -Y,R11
ST -Y,R12
ST -Y,R13
ST -Y,R14
ST -Y,R15
ST -Y,R16
ST -Y,R17
ST -Y,R18
ST -Y,R19
ST -Y,R20
ST -Y,R21
ST -Y,R22
ST -Y,R23
ST -Y,R24
ST -Y,R25
ST -Y,R26
ST -Y,R27
ST -Y,R30
ST -Y,R31
.endmacro
; Pop registers
.macro POPRS
LD R31,Y+
LD R30,Y+
LD R27,Y+
LD R26,Y+
LD R25,Y+
LD R24,Y+
LD R23,Y+
LD R22,Y+
LD R21,Y+
LD R20,Y+
LD R19,Y+
LD R18,Y+
LD R17,Y+
LD R16,Y+
LD R15,Y+
LD R14,Y+
LD R13,Y+
LD R12,Y+
LD R11,Y+
LD R10,Y+
LD R9,Y+
LD R8,Y+
LD R7,Y+
LD R6,Y+
LD R5,Y+
LD R4,Y+
LD R3,Y+
LD R2,Y+
LD R1,Y+
LD R0,Y+
.endmacro
; Push stack pointer
.macro PUSHSP
IN R16,SPH
ST -Y,R16
IN R16,SPL
ST -Y,R16
.endmacro
; Pop stack pointer
.macro POPSP
LD R16,Y+
OUT SPL,R16
LD R16,Y+
OUT SPH,R16
.endmacro
;Push SREG
.macro PUSHSREG
IN R16,SREG
ST -Y,R16
.endmacro
; Pop SREG
.macro POPSREG
LD R16,Y+
OUT SREG,R16
.endmacro
.area text(rel)
;*******************************************************************************
; START HIGHEST PRIORITY TASK READY-TO-RUN
;
; Description : This function is called by OSStart() to start the highest
; priority task that was created by your application before calling OSStart().
;
; Note(s):
; 1) The (data)stack frame is assumed to look as follows:
;
; OSTCBHighRdy->OSTCBStkPtr --> LSB of (return) stack pointer (Low memory)
; MSB of (return) stack pointer
; Flags to load in status register
; R31
; R30
; R7
; .
; .
; .
; R0 (High memory)
;
; where the stack pointer points to the task start address.
;
;
; 2) OSStartHighRdy() MUST:
; a) RCALL OSTaskSwHook() then,
; b) Set OSRunning to TRUE,
; c) Switch to the highest priority task.
;*******************************************************************************
_OSStartHighRdy::
LDS R16,_OSRunning ; Indicate that we are multitasking
INC R16
STS _OSRunning,R16 ;
LDS R30,_OSTCBHighRdy ; Let Z point to TCB of highest priority task
LDS R31,_OSTCBHighRdy+1 ; ready to run
LD R28,Z+ ; Load Y (R29:R28) pointer
LD R29,Z+ ;
POPSP ; Restore stack pointer
POPSREG ; Restore status register
POPRS ; Restore all registers
RET ; start task
;*******************************************************************************
; TASK LEVEL CONTEXT SWITCH
;
; Description : This function is called when a task makes a higher priority task
; ready-to-run.
;
; Note(s):
; 1) Upon entry,
; OSTCBCur points to the OS_TCB of the task to suspend
; OSTCBHighRdy points to the OS_TCB of the task to resume
;
; 2) The stack frame of the task to suspend looks as follows:
;
; SP +0 --> LSB of task code address
; +1 MSB of task code address (High memory)
;
; 3) The saved context of the task to resume looks as follows:
;
; OSTCBHighRdy->OSTCBStkPtr --> LSB of (return) stack pointer (Low memory)
; MSB of (return) stack pointer
; Flags to load in status register
; R31
; R30
; R7
; .
; .
; .
; R0 (High memory)
;*******************************************************************************
_OSCtxSw:: PUSHRS ; Save current task's context
PUSHSREG
PUSHSP
LDS R30,_OSTCBCur ; Z = OSTCBCur->OSTCBStkPtr
LDS R31,_OSTCBCur+1 ;
ST Z+,R28 ; Save Y (R29:R28) pointer
ST Z+,R29 ;
LDS R16,_OSPrioHighRdy ; OSPrioCur = OSPrioHighRdy
STS _OSPrioCur,R16
LDS R30,_OSTCBHighRdy ; Let Z point to TCB of highest priority task
LDS R31,_OSTCBHighRdy+1 ; ready to run
STS _OSTCBCur,R30 ; OSTCBCur = OSTCBHighRdy
STS _OSTCBCur+1,R31 ;
LD R28,Z+ ; Restore Y pointer
LD R29,Z+ ;
POPSP ; Restore stack pointer
POPSREG ; Restore status register
POPRS ; Restore all registers
RET
_OSTickISR::
PUSHRS ; Save interrupted task's context
IN R16,SREG
;move to end
; SBR R16,0x80 ; Set interrupt bit in status reg and save
ST -Y,R16
; PUSHSP
;avr-gcc ->11059200
LDI R16,256-(8000000/50/1024) ; Reload timer to overflow at a rate of 50Hz
OUT TCNT0,R16 ; at a prescaler of 1024 and 7.3728 MHz AVR clock
LDS R16,_OSIntNesting ; Notify uC/OS-II of ISR
INC R16 ;
STS _OSIntNesting,R16 ;
;why?
; SEI ; Enable interrupts
RCALL _OSTimeTick ; RCALL uC/OS-II's tick updating function
RCALL _OSIntExit ; Notify uC/OS-II about end of ISR
; POPSP
POPSREG ; Restore status register
POPRS ; Restore all registers
SEI
RET ; Note: RET instead of RETI
;*******************************************************************************
; INTERRUPT LEVEL CONTEXT SWITCH
;
; Description : This function is called by OSIntExit() to perform a context
; switch to a task that has been made ready-to-run by an ISR.
;
; Note(s):
; 1) Upon entry,
; OSTCBCur points to the OS_TCB of the task to suspend
; OSTCBHighRdy points to the OS_TCB of the task to resume
;
; 2) The stack frame of the task to suspend looks as follows:
;
; SP +0 --> LSB of return address of OSIntCtxSw() (Low memory)
; +1 MSB of return address of OSIntCtxSw()
; +2 LSB of return address of OSIntExit()
; +3 MSB of return address of OSIntExit()
; +4 LSB of task code address
; +5 MSB of task code address (High memory)
;
; 3) The saved context of the task to resume looks as follows:
;
; OSTCBHighRdy->OSTCBStkPtr --> LSB of (return) stack pointer (Low mem)
; MSB of (return) stack pointer
; Flags to load in status register
; R31
; R30
; R7
; .
; .
; .
; R0 (High memory)
;*******************************************************************************
_OSIntCtxSw::
IN R30,SPL ; Z = SP
IN R31,SPH
; ADIW R30,4 ; (Uncomment if OS_CRITICAL_METHOD is 1, see OS_CPU.H)
ADIW R30,5 ; Adjust Z to point to task return address
ST -Y,R31 ; Save SP
ST -Y,R30 ;
LDS R30,_OSTCBCur ; Z = OSTCBCur->OSTCBStkPtr
LDS R31,_OSTCBCur+1 ;
ST Z+,R28 ; Save Y pointer
ST Z+,R29 ;
LDS R16,_OSPrioHighRdy ; OSPrioCur = OSPrioHighRdy
STS _OSPrioCur,R16 ;
LDS R30,_OSTCBHighRdy ; Z = OSTCBHighRdy->OSTCBStkPtr
LDS R31,_OSTCBHighRdy+1 ;
STS _OSTCBCur,R30 ; OSTCBCur = OSTCBHighRdy
STS _OSTCBCur+1,R31 ;
LD R28,Z+ ; Restore Y pointer
LD R29,Z+ ;
POPSP ; Restore stack pointer
POPSREG ; Restore status register
POPRS ; Restore saved registers
SEI
RET
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