avra: add LD/ST

apps/zasm/README.md

@@ -191,4 +191,10 @@ the instruction after the "foo" label would be "rjmp foo+1". In zasm, it's
 "rjmp foo+2". If your expression results in an odd number, the low bit of your
 number will be ignored.
 
+Limitations:
+
+* `CALL` and `JMP` only support 16-bit numbers, not 22-bit ones.
+* `BRLO` and `BRSH` are not there. Use `BRCS` and `BRCC` instead.
+* No `high()` and `low()`. Use `&0xff` and `}8`.
+
 [libz80]: https://github.com/ggambetta/libz80

apps/zasm/avr.asm

@@ -31,14 +31,19 @@ instrNames:
 .equ	I_BRBS	16
 .db "BRBS", 0
 .db "BRBC", 0
+.equ	I_LD	18
+.db "LD", 0
+.db "ST", 0
 ; Rd(5) + Rr(5) (from here, instrTbl8)
-.equ	I_ADC	18
+.equ	I_ADC	20
 .db "ADC", 0
 .db "ADD", 0
 .db "AND", 0
 .db "ASR", 0
+.db "BCLR", 0
 .db "BLD", 0
 .db "BREAK", 0
+.db "BSET", 0
 .db "BST", 0
 .db "CLC", 0
 .db "CLH", 0
@@ -64,6 +69,7 @@ instrNames:
 .db "LAC", 0
 .db "LAS", 0
 .db "LAT", 0
+.db "LSL", 0
 .db "LSR", 0
 .db "MOV", 0
 .db "MUL", 0
@@ -83,6 +89,7 @@ instrNames:
 .db "SEH", 0
 .db "SEI", 0
 .db "SEN", 0
+.db "SER", 0
 .db "SES", 0
 .db "SET", 0
 .db "SEV", 0
@@ -90,22 +97,33 @@ instrNames:
 .db "SLEEP", 0
 .db "SUB", 0
 .db "SWAP", 0
+.db "TST", 0
 .db "WDR", 0
 .db "XCH", 0
-.equ	I_ANDI	77
+.equ	I_ANDI	84
 .db "ANDI", 0
+.db "CBR", 0
 .db "CPI", 0
 .db "LDI", 0
 .db "ORI", 0
 .db "SBCI", 0
 .db "SBR", 0
 .db "SUBI", 0
-.equ	I_RCALL	84
+.equ	I_RCALL	92
 .db "RCALL", 0
 .db "RJMP", 0
-.equ	I_CBI	86
+.equ	I_CBI	94
 .db "CBI", 0
 .db "SBI", 0
+.db "SBIC", 0
+.db "SBIS", 0
+; 32-bit
+; ZASM limitation: CALL and JMP constants are 22-bit. In ZASM, we limit
+; ourselves to 16-bit. Supporting 22-bit would incur a prohibitive complexity
+; cost. As they say, 64K words ought to be enough for anybody.
+.equ	I_CALL	98
+.db "CALL", 0
+.db "JMP", 0
 .db 0xff
 
 ; Instruction table
@@ -127,6 +145,7 @@ instrNames:
 ;        allow this kind of syntactic sugar with minimal complexity.
 ;
 ; Bit 6: Second arg is a copy of the first
+; Bit 5: Second arg is inverted (complement)
 
 ; In the same order as in instrNames
 instrTbl:
@@ -137,8 +156,10 @@ instrTbl:
 .db 0x02, 0b00001100, 0x00		; ADD Rd, Rr
 .db 0x02, 0b00100000, 0x00		; AND Rd, Rr
 .db 0x01, 0b10010100, 0b00000101	; ASR Rd
+.db 0x0b, 0b10010100, 0b10001000	; BCLR s, k
 .db 0x05, 0b11111000, 0x00		; BLD Rd, b
 .db 0x00, 0b10010101, 0b10011000	; BREAK
+.db 0x0b, 0b10010100, 0b00001000	; BSET s, k
 .db 0x05, 0b11111010, 0x00		; BST Rd, b
 .db 0x00, 0b10010100, 0b10001000	; CLC
 .db 0x00, 0b10010100, 0b11011000	; CLH
@@ -164,11 +185,12 @@ instrTbl:
 .db 0x01, 0b10010010, 0b00000110	; LAC Rd
 .db 0x01, 0b10010010, 0b00000101	; LAS Rd
 .db 0x01, 0b10010010, 0b00000111	; LAT Rd
+.db 0x41, 0b00001100, 0x00		; LSL Rd
 .db 0x01, 0b10010100, 0b00000110	; LSR Rd
-.db 0x00, 0b00000000, 0b00000000	; NOP
 .db 0x02, 0b00101100, 0x00		; MOV Rd, Rr
 .db 0x02, 0b10011100, 0x00		; MUL Rd, Rr
 .db 0x01, 0b10010100, 0b00000001	; NEG Rd
+.db 0x00, 0b00000000, 0b00000000	; NOP
 .db 0x02, 0b00101000, 0x00		; OR Rd, Rr
 .db 0x87, 0b10111000, 0x00		; OUT A, Rr (Bit 7)
 .db 0x01, 0b10010000, 0b00001111	; POP Rd
@@ -183,6 +205,7 @@ instrTbl:
 .db 0x00, 0b10010100, 0b01011000	; SEH
 .db 0x00, 0b10010100, 0b01111000	; SEI
 .db 0x00, 0b10010100, 0b00101000	; SEN
+.db 0x0a, 0b11101111, 0b00001111	; SER Rd
 .db 0x00, 0b10010100, 0b01001000	; SES
 .db 0x00, 0b10010100, 0b01101000	; SET
 .db 0x00, 0b10010100, 0b00111000	; SEV
@@ -190,22 +213,29 @@ instrTbl:
 .db 0x00, 0b10010101, 0b10001000	; SLEEP
 .db 0x02, 0b00011000, 0x00		; SUB Rd, Rr
 .db 0x01, 0b10010100, 0b00000010	; SWAP Rd
+.db 0x41, 0b00100000, 0x00		; TST Rd (Bit 6)
 .db 0x00, 0b10010101, 0b10101000	; WDR
 .db 0x01, 0b10010010, 0b00000100	; XCH Rd
 ; Rd(4) + K(8): XXXXKKKK ddddKKKK
-.db 0x04, 0b01110000, 0x00		; ANDI
+.db 0x04, 0b01110000, 0x00		; ANDI Rd, K
-.db 0x04, 0b00110000, 0x00		; CPI
+.db 0x24, 0b01110000, 0x00		; CBR Rd, K (Bit 5)
-.db 0x04, 0b11100000, 0x00		; LDI
+.db 0x04, 0b00110000, 0x00		; CPI Rd, K
-.db 0x04, 0b01100000, 0x00		; ORI
+.db 0x04, 0b11100000, 0x00		; LDI Rd, K
-.db 0x04, 0b01000000, 0x00		; SBCI
+.db 0x04, 0b01100000, 0x00		; ORI Rd, K
-.db 0x04, 0b01100000, 0x00		; SBR
+.db 0x04, 0b01000000, 0x00		; SBCI Rd, K
-.db 0x04, 0b01010000, 0x00		; SUBI
+.db 0x04, 0b01100000, 0x00		; SBR Rd, K
+.db 0x04, 0b01010000, 0x00		; SUBI Rd, K
 ; k(12): XXXXkkkk kkkkkkkk
 .db 0x08, 0b11010000, 0x00		; RCALL k
 .db 0x08, 0b11000000, 0x00		; RJMP k
 ; A(5) + bit: XXXXXXXX AAAAAbbb
 .db 0x09, 0b10011000, 0x00		; CBI A, b
 .db 0x09, 0b10011010, 0x00		; SBI A, b
+.db 0x09, 0b10011001, 0x00		; SBIC A, b
+.db 0x09, 0b10011011, 0x00		; SBIS A, b
+; k(16) (well, k(22)...)
+.db 0x08, 0b10010100, 0b00001110	; CALL k
+.db 0x08, 0b10010100, 0b00001100	; JMP k
 
 ; Same signature as getInstID in instr.asm
 ; Reads string in (HL) and returns the corresponding ID (I_*) in A. Sets Z if
@@ -253,8 +283,11 @@ parseInstruction:
 	ld	bc, 0
 	ld	e, a		; Let's keep that instrID somewhere safe
 	; First, let's fetch our table row
-	cp	I_ADC
+	cp	I_LD
 	jp	c, .BR		; BR is special, no table row
+	jp	z, .LD		; LD is special
+	cp	I_ADC
+	jp	c, .ST		; ST is special
 
 	; *** Step 2: parse arguments
 	sub	I_ADC		; Adjust index for table
@@ -267,7 +300,7 @@ parseInstruction:
 	push	hl \ pop ix	; IX is now our tblrow
 	ld	hl, 0
 	or	a
-	jr	z, .spit	; No arg? spit right away
+	jp	z, .spit	; No arg? spit right away
 	and	0xf		; lower nibble
 	dec	a		; argspec index is 1-based
 	ld	hl, argSpecs
@@ -290,6 +323,8 @@ parseInstruction:
 	call	nz, .swapHL	; Bit 7 set, swap H and L again!
 	bit	6, (ix)
 	call	nz, .cpHintoL	; Bit 6 set, copy H into L
+	bit	5, (ix)
+	call	nz, .invL	; Bit 5 set, invert L
 	ld	a, e		; InstrID
 	cp	I_ANDI
 	jr	c, .spitRegular
@@ -297,12 +332,18 @@ parseInstruction:
 	jr	c, .spitRdK8
 	cp	I_CBI
 	jr	c, .spitk12
-	; spit A(5) + bit
+	cp	I_CALL
+	jr	c, .spitA5Bit
+	; Spit k(16)
+	call	.spit		; spit 16-bit const upcode
+	; divide HL by 2 (PC deals with words, not bytes)
+	srl h \ rr l
+	; spit 16-bit K, LSB first
+	ld	a, l
+	call	ioPutB
 	ld	a, h
-	rla \ rla \ rla
+	jp	ioPutB
-	or	l
+
-	ld	c, a
-	jr	.spit
 .spitRegular:
 	; Regular process which places H and L, ORring it with upcode. Works
 	; in most cases.
@@ -319,6 +360,8 @@ parseInstruction:
 .spitk12:
 	; k(12) in HL
 	; We're doing the same dance as in _readk7. See comments there.
+	call	zasmIsFirstPass
+	jr	z, .spit
 	ld	de, 0xfff
 	add	hl, de
 	jp	c, unsetZ	; Carry? number is way too high.
@@ -339,6 +382,12 @@ parseInstruction:
 	and	0xf
 	ld	b, a
 	jr	.spit
+.spitA5Bit:
+	ld	a, h
+	sla a \ rla \ rla
+	or	l
+	ld	c, a
+	jr	.spit
 
 .spit:
 	; LSB is spit *before* MSB
@@ -405,6 +454,40 @@ parseInstruction:
 	; bit in H, k in L.
 	jr	.spitBR2
 
+.LD:
+	ld	h, 'R'
+	ld	l, 'z'
+	call	_parseArgs
+	ret	nz
+	ld	d, 0b10000000
+	jr	.LDST
+.ST:
+	ld	h, 'z'
+	ld	l, 'R'
+	call	_parseArgs
+	ret	nz
+	ld	d, 0b10000010
+	call	.swapHL
+	; continue to .LDST
+
+.LDST:
+	; Rd in H, Z in L, base upcode in D
+	call	.placeRd
+	; We're spitting LSB first, so let's compose it.
+	ld	a, l
+	and	0b00001111
+	or	c
+	call	ioPutB
+	; Now, MSB's bit 4 is L's bit 4. How convenient!
+	ld	a, l
+	and	0b00010000
+	or	d
+	or	b
+	; MSB composed!
+	call	ioPutB
+	cp	a		; ensure Z
+	ret
+
 ; local routines
 ; place number in H in BC at position .......d dddd....
 ; BC is assumed to be 0
@@ -441,6 +524,12 @@ parseInstruction:
 	ld	l, h
 	ret
 
+.invL:
+	ld	a, l
+	cpl
+	ld	l, a
+	ret
+
 ; Argspecs: two bytes describing the arguments that are accepted. Possible
 ; values:
 ;
@@ -453,6 +542,9 @@ parseInstruction:
 ; 'D' - A double-length number which will fill whole HL.
 ; 'R' - an r5 value: r0-r31
 ; 'r' - an r4 value: r16-r31
+; 'z' - an indirect register (X, Y or Z), with our without post-inc/pre-dec
+;       indicator. This will result in a 5-bit number, from which we can place
+;	bits 3:0 to upcode's 3:0 and bit 4 at upcode's 12 in LD and ST.
 ;
 ; All arguments accept expressions, even 'r' ones: in 'r' args, we start by
 ; looking if the arg starts with 'r' or 'R'. If yes, it's a simple 'rXX' value,
@@ -468,6 +560,8 @@ argSpecs:
 	.db	'R', 'A'	; Rd(5) + A(6)
 	.db	'D', 0		; K(12)
 	.db	'a', 'b'	; A(5) + bit
+	.db	'r', 0		; Rd(4)
+	.db	'b', 0		; bit
 
 ; Parse arguments from I/O according to specs in HL
 ; H for first spec, L for second spec
@@ -528,6 +622,8 @@ _parseArgs:
 	jr	z, _readK8
 	cp	'D'
 	jr	z, _readDouble
+	cp	'z'
+	jp	z, _readz
 	ret			; something's wrong
 
 _readBit:
@@ -563,6 +659,10 @@ _readk7:
 	push	ix
 	call	parseExpr
 	jr	nz, .end
+	; If we're in first pass, stop now. The value of HL doesn't matter and
+	; truncation checks might falsely fail.
+	call	zasmIsFirstPass
+	jr	z, .end
 	; IX contains an absolute value. Turn this into a -64/+63 relative
 	; value by subtracting PC from it. However, before we do that, let's
 	; add 0x7f to it, which we'll remove later. This will simplify bounds
@@ -653,4 +753,63 @@ _readExpr:
 	pop	ix
 	ret
 
+; Parse one of the following: X, Y, Z, X+, Y+, Z+, -X, -Y, -Z.
+; For each of those values, return a 5-bit value than can then be interleaved
+; with LD or ST upcodes.
+_readz:
+	call	strlen
+	cp	3
+	jp	nc, unsetZ	; string too long
+	; Let's load first char in A and second in A'. This will free HL
+	ld	a, (hl)
+	ex	af, af'
+	inc	hl
+	ld	a, (hl)		; Good, HL is now free
+	ld	hl, .tblStraight
+	or	a
+	jr	z, .parseXYZ	; Second char null? We have a single char
+	; Maybe +
+	cp	'+'
+	jr	nz, .skip
+	; We have a +
+	ld	hl, .tblInc
+	jr	.parseXYZ
+.skip:
+	; Maybe a -
+	ex	af, af'
+	cp	'-'
+	ret	nz		; we have nothing
+	; We have a -
+	ld	hl, .tblDec
+	; continue to .parseXYZ
+.parseXYZ:
+	; We have X, Y or Z in A'
+	ex	af, af'
+	call	upcase
+	; Now, let's place HL
+	cp	'X'
+	jr	z, .fetch
+	inc	hl
+	cp	'Y'
+	jr	z, .fetch
+	inc	hl
+	cp	'Z'
+	ret	nz		; error
+.fetch:
+	ld	a, (hl)
+	; Z already set from earlier cp
+	ret
+
+.tblStraight:
+	.db	0b11100		; X
+	.db	0b01000		; Y
+	.db	0b00000		; Z
+.tblInc:
+	.db	0b11101		; X+
+	.db	0b11001		; Y+
+	.db	0b10001		; Z+
+.tblDec:
+	.db	0b11110		; -X
+	.db	0b11010		; -Y
+	.db	0b10010		; -Z
 

avr/ops.txt

@@ -21,8 +21,8 @@ IJMP, NOP, RET, RETI, SEC, SEH, SEI, SEN, SES, SET, SEV, SEZ, SLEEP, SPM*, WDR
 
 XXXX XXXd dddd XXXX
 
-ASR, COM, DEC, ELPM*, INC, LAC, LAS, LAT, LD*, LPM*, LSR, NEG, POP, PUSH, ROR,
+ASR, COM, DEC, ELPM*, INC, LAC, LAS, LAT, LD*, LPM*, LSL*, LSR, NEG, POP, PUSH,
-ST*, SWAP, XCH
+ROR, ST*, SWAP, XCH
 
 ## Rd(5) + Rr(5)
 

tools/tests/avra/blink_tn45.asm

@@ -1,4 +1,3 @@
-; TODO: implement instructions that are commented out
 ; REGISTER USAGE
 ;
 ; R1: overflow counter

tools/tests/avra/seg7multiplex.asm

@@ -0,0 +1,343 @@
+; This is a copy of my seg7multiplex main program, translated for zasm.
+; The output of zasm was verified against avra's.
+
+; 7-segments multiplexer for an ATtiny45
+;
+; Register usage
+; R0: Digit on AFF1 (rightmost, QH on the SR)
+; R1: Digit on AFF2 (QG on the SR)
+; R2: Digit on AFF3 (QF on the SR)
+; R3: Digit on AFF4 (leftmost, QE on the SR)
+; R5: always zero
+; R6: generic tmp value
+; R16: generic tmp value
+; R18: value to send to the SR. cleared at every SENDSR call
+;      in input mode, holds the input buffer
+; R30: (low Z) current digit being refreshed. cycles from 0 to 3
+;
+; Flags on GPIOs
+; GPIOR0 - bit 0: Whether we need to refresh the display
+; GPIOR0 - bit 1: Set when INT_INT0 has received a new bit
+; GPIOR0 - bit 2: The value of the new bit received
+; GPIOR0 - bit 4: input mode enabled
+
+; Notes on register usage
+; R0 - R3: 4 low bits are for digit, 5th bit is for dot. other bits are unused.
+;
+; Notes on AFF1-4
+; They are reversed (depending on how you see things...). They read right to
+; left. That means that AFF1 is least significant, AFF4 is most.
+;
+; Input mode counter
+; When in input mode, TIMER0_OVF, instead of setting the refresh flag, increases
+; the counter. When it reaches 3, we timeout and consider input invalid.
+;
+; Input procedure
+;
+; Input starts at INT_INT0. What it does there is very simple: is sets up a flag
+; telling it received something and conditionally sets another flag with the
+; value of the received bit.
+;
+; While we do that, we have the input loop eagerly checking for that flag. When
+; it triggers, it records the bit in R18. The way it does so is that it inits
+; R18 at 1 (not 0), then for every bit, it left shifts R18, then adds the new
+; bit. When the 6th bit of R18 is set, it means we have every bit we need, we
+; can flush it into Z.
+
+; Z points directly to R3, then R2, then R1, then R0. Because display refresh
+; is disabled during input, it won't result in weird displays, and because
+; partial numbers result in error display, then partial result won't lead to
+; weird displays, just error displays.
+;
+; When input mode begins, we change Z to point to R3 (the first digit we
+; receive) and we decrease the Z pointer after every digit we receive. When we
+; receive the last bit of the last digit and that we see that R30 is 0, we know
+; that the next (and last) digit is the checksum.
+
+.inc "avr.h"
+.inc "tn254585.h"
+.inc "tn45.h"
+
+; pins
+.equ RCLK 0	; on PORTB
+.equ SRCLK 3	; on PORTB
+.equ SER_DP 4	; on PORTB
+.equ INSER 1	; on PORTB
+
+; Let's begin!
+
+.org 0x0000
+        RJMP    MAIN
+	RJMP	INT_INT0
+	RETI	; PCINT0
+	RETI	; TIMER1_COMPA
+	RETI	; TIMER1_OVF
+	RJMP	INT_TIMER0_OVF
+
+MAIN:
+	LDI	R16, RAMEND&0xff
+        OUT	SPL, R16
+        LDI	R16, RAMEND}8
+	OUT	SPH, R16
+
+	SBI	DDRB, RCLK
+	SBI	DDRB, SRCLK
+	SBI	DDRB, SER_DP
+
+	; we generally keep SER_DP high to avoid lighting DP
+	SBI	PORTB, SER_DP
+
+	; target delay: 600us. At 1Mhz, that's 75 ticks with a 1/8 prescaler.
+	LDI	R16, 0x02	; CS01, 1/8 prescaler
+	OUT	TCCR0B, R16
+	LDI	R16, 0xb5	; TOP - 75 ticks
+	OUT	TCNT0, R16
+
+	; Enable TIMER0_OVF
+	IN	R16, TIMSK
+	ORI	R16, 0x02	; TOIE0
+	OUT	TIMSK, R16
+
+	; Generate interrupt on rising edge of INT0
+	IN	R16, MCUCR
+	ORI	R16, 0b00000011	; ISC00 + ISC01
+	OUT	MCUCR, R16
+	IN	R16, GIMSK
+	ORI	R16, 0b01000000	; INT0
+	OUT	GIMSK, R16
+
+	; we never use indirect addresses above 0xff through Z and never use
+	; R31 in other situations. We can set it once and forget about it.
+	CLR	R31	; high Z
+
+	; put 4321 in R2-5
+	CLR	R30	; low Z
+	LDI	R16, 0x04
+	ST	Z+, R16		; 4
+	DEC	R16
+	ST	Z+, R16		; 3
+	DEC	R16
+	ST	Z+, R16		; 2
+	DEC	R16
+	ORI	R16, 0b00010000	; DP
+	ST	Z, R16		; 1
+	CLR	R30		; replace Z to 0
+
+	SEI
+
+LOOP:
+	RCALL	INPT_CHK	; verify that we shouldn't enter input mode
+	SBIC	GPIOR0, 0	; refesh flag cleared? skip next
+	RCALL	RDISP
+        RJMP    LOOP
+
+; ***** DISPLAY *****
+
+; refresh display with current number
+RDISP:
+	; First things first: setup the timer for the next time
+	LDI	R16, 0xb5	; TOP - 75 ticks
+	OUT	TCNT0, R16
+	CBI	GPIOR0, 0	; Also, clear the refresh flag
+
+	; Let's begin with the display selector. We select one display at once
+	; (not ready for multi-display refresh operations yet). Let's decode our
+	; binary value from R30 into R16.
+	MOV	R6, R30
+	INC	R6		; we need values 1-4, not 0-3
+	LDI	R16, 0x01
+RDISP1:
+	DEC	R6
+	BREQ	RDISP2		; == 0? we're finished
+	LSL	R16
+	RJMP	RDISP1
+
+	; select a digit to display
+	; we do so in a clever way: our registers just happen to be in SRAM
+	; locations 0x00, 0x01, 0x02 and 0x03. Handy eh!
+RDISP2:
+	LD	R18, Z+		; Indirect load of Z into R18 then increment
+	CPI	R30, 4
+	BRCS	RDISP3		; lower than 4 ? don't reset
+	CLR	R30		; not lower than 4? reset
+
+	; in the next step, we're going to join R18 and R16 together, but
+	; before we do, we have one thing to process: R18's 5th bit. If it's
+	; high, it means that DP is highlighted. We have to store this
+	; information in R6 and use it later. Also, we have to clear the higher
+	; bits of R18.
+RDISP3:
+	SBRC	R18, 4		; 5th bit cleared? skip next
+	INC	R6		; if set, then set R6 as well
+	ANDI	R18, 0xf	; clear higher bits
+
+	; Now we have our display selector in R16 and our digit to display in
+	; R18. We want it all in R18.
+	SWAP	R18		; digit goes in high "nibble"
+	OR	R18, R16
+
+	; While we send value to the shift register, SER_DP will change.
+	; Because we want to avoid falsely lighting DP, we need to disable
+	; output (disable OE) while that happens. This is why we set RCLK,
+	; which is wired to OE too, HIGH (OE disabled) at the beginning of
+	; the SR operation.
+	;
+	; Because RCLK was low before, this triggers a "buffer clock" on
+	; the SR, but it doesn't matter because the value that was there
+	; before has just been invalidated.
+	SBI	PORTB, RCLK	; high
+	RCALL	SENDSR
+	; Flush out the buffer with RCLK
+	CBI	PORTB, RCLK	; OE enabled, but SR buffer isn't flushed
+	NOP
+	SBI	PORTB, RCLK	; SR buffer flushed, OE disabled
+	NOP
+	CBI	PORTB, RCLK	; OE enabled
+
+	; We're finished! Oh no wait, one last thing: should we highlight DP?
+	; If we should, then we should keep SER_DP low rather than high for this
+	; SR round.
+	SBI	PORTB, SER_DP	; SER_DP generally kept high
+	SBRC	R6, 0		; R6 is cleared? skip DP set
+	CBI	PORTB, SER_DP	; SER_DP low highlight DP
+
+	RET			; finished for real this time!
+
+; send R18 to shift register.
+; We send highest bits first so that QH is the MSB and QA is the LSB
+; low bits (QD - QA) control display's power
+; high bits (QH - QE) select the glyph
+SENDSR:
+	LDI	R16, 8		; we will loop 8 times
+	CBI	PORTB, SER_DP	; low
+	SBRC	R18, 7	; if latest bit isn't cleared, set SER_DP high
+	SBI	PORTB, SER_DP	; high
+	RCALL	TOGCP
+	LSL	R18		; shift our data left
+	DEC	R16
+	BRNE	SENDSR+2	; not zero yet? loop! (+2 to avoid reset)
+	RET
+
+; toggle SRCLK, waiting 1us between pin changes
+TOGCP:
+	CBI	PORTB, SRCLK	; low
+	NOP			; At 1Mhz, this is enough for 1us
+	SBI	PORTB, SRCLK	; high
+	RET
+
+; ***** INPUT MODE *****
+
+; check whether we should enter input mode and enter it if needed
+INPT_CHK:
+	SBIS	GPIOR0, 1	; did we just trigger INT_INT0?
+	RET			; no? return
+	; yes? continue in input mode
+
+; Initialize input mode and start the loop
+INPT_BEGIN:
+	SBI	GPIOR0, 4	; enable input mode
+	CBI	GPIOR0, 1	; The first trigger was an empty one
+
+	; At 1/8 prescaler, a "full" counter overflow is 2048us. That sounds
+	; about right for an input timeout. So we co the easy route and simply
+	; clear TCNT0 whenever we want to reset the timer
+	OUT	TCNT0, R5	; R5 == 0
+	CBI	GPIOR0, 0	; clear refresh flag in case it was just set
+	LDI	R30, 0x04	; make Z point on R3+1 (we use pre-decrement)
+	LDI	R18, 0x01	; initialize input buffer
+
+; loop in input mode. When in input mode, we don't refresh the display, we use
+; all our processing power to process input.
+INPT_LOOP:
+	RCALL	INPT_READ
+
+	; Check whether we've reached timeout
+	SBIC	GPIOR0, 0	; refesh flag cleared? skip next
+	RCALL	INPT_TIMEOUT
+
+	SBIC	GPIOR0, 4	; input mode cleared? skip next, to INPT_END
+	RJMP	INPT_LOOP	; not cleared? loop
+
+INPT_END:
+	; We received all our date or reached timeout. let's go back in normal
+	; mode.
+	CLR	R30		; Ensure Z isn't out of bounds
+	SBI	GPIOR0, 0	; set refresh flag so we start refreshing now
+	RET
+
+; Read, if needed, the last received bit
+INPT_READ:
+	SBIS	GPIOR0, 1
+	RET			; flag cleared? nothing to do
+
+	; Flag is set, we have to read
+	CBI	GPIOR0, 1	; unset flag
+	LSL	R18
+	SBIC	GPIOR0, 2	; data flag cleared? skip next
+	INC	R18
+
+	; Now, let's check if we have our 5 digits
+	SBRC	R18, 5		; 6th bit cleared? nothing to do
+	RCALL	INPT_PUSH
+
+	OUT	TCNT0, R5	; clear timeout counter
+
+	RET
+
+; Push the digit currently in R18 in Z and reset R18.
+INPT_PUSH:
+	ANDI	R18, 0b00011111	; Remove 6th bit flag
+
+	TST	R30		; is R30 zero?
+	BREQ	INPT_CHECKSUM	; yes? it means we're at checksum phase.
+
+	; Otherwise, its a regular digit push
+	ST	-Z, R18
+	LDI	R18, 0x01
+	RET
+
+INPT_CHECKSUM:
+	CBI	GPIOR0, 4	; clear input mode, whether we error or not
+	MOV	R16, R0
+	ADD	R16, R1
+	ADD	R16, R2
+	ADD	R16, R3
+	; only consider the first 5 bits of the checksum since we can't receive
+	; more. Otherwise, we couldn't possibly validate a value like 9999
+	ANDI	R16, 0b00011111
+	CP	R16, R18
+	BRNE	INPT_ERROR
+	RET
+
+INPT_TIMEOUT:
+	CBI	GPIOR0, 4	; timeout reached, clear input flag
+	; continue to INPT_ERROR
+
+INPT_ERROR:
+	LDI	R16, 0x0c	; some weird digit
+	MOV	R0, R16
+	MOV	R1, R16
+	MOV	R2, R16
+	MOV	R3, R16
+	RET
+
+; ***** INTERRUPTS *****
+
+; Record received bit
+; The main loop has to be fast enough to process that bit before we receive the
+; next one!
+; no SREG fiddling because no SREG-modifying instruction
+INT_INT0:
+	CBI	GPIOR0, 2	; clear received data
+	SBIC	PINB, INSER	; INSER clear? skip next
+	SBI	GPIOR0, 2	; INSER set? record this
+	SBI	GPIOR0, 1	; indicate that we've received a bit
+	RETI
+
+; Set refresh flag whenever timer0 overflows
+; no SREG fiddling because no SREG-modifying instruction
+INT_TIMER0_OVF:
+	SBI	GPIOR0, 0
+	RETI
+
+

tools/tests/avra/test1.asm

@@ -14,3 +14,13 @@ rcall	baz
 baz:
 out	0x2e, r12
 in	r0, 0x9
+cbr	r31, 0xff
+sbis	22, 5
+ser	r19
+bset	4
+bclr	7
+call	foo
+jmp	bar
+mov	r6, r30
+lsl	r3
+tst	r12

tools/tests/avra/testldst.asm

@@ -0,0 +1,18 @@
+ld r0, X
+ld r1, Y
+ld r2, Z
+ld r3, X+
+ld r4, Y+
+ld r5, Z+
+ld r6, -X
+ld r7, -Y
+ld r8, -Z
+st X, r9
+st Y, r10
+st Z, r11
+st X+, r12
+st Y+, r13
+st Z+, r14
+st -X, r15
+st -Y, r16
+st -Z, r17

tools/tests/avra/testldst.expected

@@ -0,0 +1,2 @@
+<0C>€ €=<3D>I<EFBFBD>Q<EFBFBD>n<EFBFBD>z<EFBFBD>‚<EFBFBD>ś’¨‚°‚Í’Ů’á’ţ’
+““