203 lines
5.2 KiB
NASM
203 lines
5.2 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2023 by Martin Preuss
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; email : martin@libchipcard.de
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;
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; ***************************************************************************
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; * This file is part of the project "AqHome". *
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; * Please see toplevel file COPYING of that project for license details. *
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; ***************************************************************************
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; ===========================================================================
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;
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; Macros for working with message buffers.
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;
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; Helpfull defines:
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; - COM2_BUFFER_NUM number of buffers to provide
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; - COM2_BUFFER_SIZE size of each buffer (CAVE: change COM2_M_BufferPosToX when changing value!)
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;
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; Variables:
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; - buffersUsed: .byte 1 holds number of buffers in use
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; - maxBuffersUsed: .byte 1 holds max number of buffers every in use at the same time
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; - buffersWritePos: .byte 1 holds current write pos
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; - buffersReadPos: .byte 1 holds current read pos
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; - buffers: .byte COM2_BUFFER_SIZE*COM2_BUFFER_NUM
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; ---------------------------------------------------------------------------
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; @macro COM2_M_BufferAlloc
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;
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; Allocate a message buffer.
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;
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; COM2_M_BufferAlloc COM2_BUFFER_NUM, com2MaxBuffersUsed, com2RecvBuffersUsed, com2RecvBuffersWritePos
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;
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; @param %0 max number of buffers
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; @param %1 pointer to byte containing max number of buffers ever used
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; @param %2 pointer to byte containing number of buffers currently in use
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; @param %3 pointer to byte containing the write pointer
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; @return CFLAG set if okay, clear otherwise
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; @return X pos to allocated buffer
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; @clobbers R16, R17, R21
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.macro COM2_M_BufferAlloc
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in r21, SREG ; save global interrupt enable bit from SREG
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cli
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lds r17, @2
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cpi r17, @0
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brcc l_error ; no buffer available
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inc r17 ; increment number of buffers used
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sts @2, r17 ; store new value
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lds r16, @1 ; calc max buffers used
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cp r16, r17
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brcc l0
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sts @1, r17
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l0:
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lds r16, @3 ; get current write pos
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mov r17, r16 ; increment for next call
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inc r17
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cpi r17, @0 ; CF set if COM_BUFFER_NUM > R17
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brcs l1
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clr r17 ; wraparound
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l1:
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sts @3, r17 ; store new writepos for next caller
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rcall COM2_BufferPosToX ; (R16, R17)
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out SREG, r21 ; restore global interrupt enable bit in SREG
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sec
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rjmp l_end
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l_error:
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out SREG, r21
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clc
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l_end:
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.endmacro
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; @end
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; ---------------------------------------------------------------------------
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; @macro COM2_M_BufferDeallocBack
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;
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; Release a transfer buffer at the end of the list by decreasing the write pos.
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; This releases the last allocated buffer!
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;
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; COM2_M_BufferDeallocBack COM2_BUFFER_NUM, com2RecvBuffersUsed, com2RecvBuffersWritePos
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;
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; @param %0 maximum number of buffers
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; @param %1 pointer to a byte containing number of buffers used
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; @param %2 pointer to a byte containing current write pos
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; @return CFLAG set if okay, clear otherwise
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; @clobbers r16, r17, r21
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.macro COM2_M_BufferDeallocBack
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in r21, SREG ; save global interrupt enable bit from SREG
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cli
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lds r17, @1
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tst r17
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breq l_error ; no buffer allocated, nothing to release
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dec r17
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sts @1, r17 ; store new value
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lds r17, @2
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tst r17 ; 0?
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brne l1 ; nope go directly decrement r17
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ldi r17, @0 ; wrap-around
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l1:
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dec r17
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sts @2, r17
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out SREG, r21
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sec
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rjmp l_end
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l_error:
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out SREG, r21
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clc
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l_end:
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.endmacro
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; @end
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; ---------------------------------------------------------------------------
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; @macro COM2_M_BufferDeallocFront
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;
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; Release a transfer buffer by increasing the read pos.
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;
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; COM2_M_BufferDeallocFront COM2_BUFFER_NUM com2RecvBuffersUsed com2RecvBuffersReadPos
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;
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; @param %0 maximum number of buffers
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; @param %1 pointer to a byte containing number of buffers used
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; @param %2 pointer to a byte containing current read pos
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; @return CFLAG set if okay, clear otherwise
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; @clobbers r16, r17, r21
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.macro COM2_M_BufferDeallocFront
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in r21, SREG ; save global interrupt enable bit from SREG
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cli
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lds r17, @1
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tst r17
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breq l_error ; no buffer allocated, nothing to release
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dec r17
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sts @1, r17 ; store new value
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lds r17, @2
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inc r17
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cpi r17, @0
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brcs l1
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clr r17 ; wrap-around
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l1:
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sts @2, r17
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out SREG, r21
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sec
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rjmp l_end
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l_error:
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out SREG, r21
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clc
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l_end:
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.endmacro
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; @end
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; ---------------------------------------------------------------------------
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; @macro COM2_M_BufferPosToX
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;
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; Get a pointer to the SRAM position of the given buffer.
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; CAVE: Code must correspond to COM2_BUFFER_SIZE!!
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;
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; COM2_M_BufferPosToX com2RecvBuffers
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;
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; @param %0 pointer to a 2 byte var containing pointer to buffers
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; @param R16 buffer number (starting with 0)
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; @return X pointer to buffer in SRAM
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; @clobbers R16, R17
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.macro COM2_M_BufferPosToX
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; calculate offset
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clr r17
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mov xl, r16
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clr xh
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lsl xl
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rol xh ; *2
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add xl, r16
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adc xh, r17 ; *3
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lsl xl
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rol xh ; *6
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lsl xl
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rol xh ; *12
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lsl xl
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rol xh ; *24
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; add base position of buffers
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ldi r16, LOW(@0)
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ldi r17, HIGH(@0)
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add xl, r16
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adc xh, r17
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.endmacro
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; @end
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