apps/zasm/README.md

@@ -178,17 +178,4 @@ arguments are separated by commas.
 To assemble an AVR assembler, use the `gluea.asm` file instead of the regular
 one.
 
-Note about AVR and PC: In most assemblers, arithmetics for instructions
-addresses have words (two bytes) as their basic unit because AVR instructions
-are either 16bit in length or 32bit in length. All addresses constants in
-upcodes are in words. However, in zasm's core logic, PC is in bytes (because z80
-upcodes can be 1 byte).
-
-The AVR assembler, of course, correctly translates byte PCs to words when
-writing upcodes, however, when you write your expressions, you need to remember
-to treat with bytes. For example, in a traditional AVR assembler, jumping to
-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.
-
 [libz80]: https://github.com/ggambetta/libz80

apps/zasm/avr.asm

@@ -8,10 +8,11 @@
 ; categories, and then alphabetically. Categories are ordered so that the 8bit
 ; opcodes come first, then the 16bit ones. 0xff ends the chain
 instrNames:
-; Branching instructions. They are all shortcuts to BRBC/BRBS. These are not in
-; alphabetical order, but rather in "bit order". All "bit set" instructions
-; first (10th bit clear), then all "bit clear" ones (10th bit set). Inside this
-; order, they're then in "sss" order (bit number alias for BRBC/BRBS).
+; Branching instructions. They are all shortcuts to BRBC/BRBS. Their respective
+; bits are listed in instrBRBits. These are not in alphabetical order, but
+; rather in "bit order". All "bit set" instructions first (10th bit clear), then
+; all "bit clear" ones (10th bit set). Inside this order, they're then in "sss"
+; order (bit number alias for BRBC/BRBS)
 .db "BRCS", 0
 .db "BREQ", 0
 .db "BRMI", 0
@@ -31,7 +32,7 @@ instrNames:
 .equ	I_BRBS	16
 .db "BRBS", 0
 .db "BRBC", 0
-; Rd(5) + Rr(5) (from here, instrUpMasks1)
+; Rd(5) + Rr(5)
 .equ	I_ADC	18
 .db "ADC", 0
 .db "ADD", 0
@@ -46,21 +47,8 @@ instrNames:
 .db "OR", 0
 .db "SBC", 0
 .db "SUB", 0
-.equ	I_ANDI	31
-.db "ANDI", 0
-.db "CPI", 0
-.db "LDI", 0
-.db "ORI", 0
-.db "SBCI", 0
-.db "SBR", 0
-.db "SUBI", 0
-.equ	I_BLD	38
-.db "BLD", 0
-.db "BST", 0
-.db "SBRC", 0
-.db "SBRS", 0
-; no arg (from here, instrUpMasks2)
-.equ	I_BREAK	42
+; no arg
+.equ	I_BREAK	31
 .db "BREAK", 0
 .db "CLC", 0
 .db "CLH", 0
@@ -88,7 +76,7 @@ instrNames:
 .db "SLEEP", 0
 .db "WDR", 0
 ; Rd(5)
-.equ	I_ASR	68
+.equ	I_ASR	57
 .db "ASR", 0
 .db "COM", 0
 .db "DEC", 0
@@ -123,20 +111,6 @@ instrUpMasks1:
 .db 0b00101000			; OR
 .db 0b00001000			; SBC
 .db 0b00011000			; SUB
-; Rd(4) + K(8): XXXXKKKK ddddKKKK
-.db 0b01110000			; ANDI
-.db 0b00110000			; CPI
-.db 0b11100000			; LDI
-.db 0b01100000			; ORI
-.db 0b01000000			; SBCI
-.db 0b01100000			; SBR
-.db 0b01010000			; SUBI
-; Rd(5) + bit: XXXXXXXd ddddXbbb: lonely bit in LSB is 0 in all cases, so we
-; ignore it.
-.db 0b11111000			; BLD
-.db 0b11111010			; BST
-.db 0b11111100			; SBRC
-.db 0b11111110			; SBRS
 
 ; 16-bit constant masks associated with each instruction. In the same order as
 ; in instrNames
@@ -184,6 +158,25 @@ instrUpMasks2:
 .db 0b10010100, 0b00000010	; SWAP
 .db 0b10010010, 0b00000100	; XCH
 
+instrBRBits:
+; 1st bit is 3rd bit of MSB and the other 3 are the lower bits of LSB
+.db 0b0000	; BRCS
+.db 0b0001	; BREQ
+.db 0b0010	; BRMI
+.db 0b0011	; BRVS
+.db 0b0100	; BRLT
+.db 0b0101	; BRHS
+.db 0b0110	; BRTS
+.db 0b0111	; BRIE
+.db 0b1000	; BRCC
+.db 0b1001	; BRNE
+.db 0b1010	; BRPL
+.db 0b1011	; BRVC
+.db 0b1100	; BRGE
+.db 0b1101	; BRHC
+.db 0b1110	; BRTC
+.db 0b1111	; BRID
+
 ; Same signature as getInstID in instr.asm
 ; Reads string in (HL) and returns the corresponding ID (I_*) in A. Sets Z if
 ; there's a match.
@@ -222,29 +215,24 @@ getInstID:
 parseInstruction:
 	; BC, during .spit, is ORred to the spitted opcode.
 	ld	bc, 0
-	; Save Instr ID in D, which is less volatile than A. In almost all
-	; cases, we fetch the opcode constant at the end of the processing.
-	ld	d, a
 	cp	I_ADC
 	jp	c, .BR
-	cp	I_ANDI
-	jr	c, .spitRd5Rr5
-	cp	I_BLD
-	jr	c, .spitRdK8
 	cp	I_BREAK
-	jr	c, .spitRdBit
+	jr	c, .spitRd5Rr5
 	cp	I_ASR
 	jr	c, .spitNoArg
 	; spitRd5
+	ld	d, a		; save A for later
 	call	.readR5
 	ret	nz
 	call	.placeRd
+	ld	a, d		; restore A
 	; continue to .spitNoArg
 .spitNoArg:
 	call	.getUp2
 	jr	.spit
-
 .spitRd5Rr5:
+	ld	d, a		; save A for later
 	call	.readR5
 	ret	nz
 	call	.placeRd
@@ -263,49 +251,10 @@ parseInstruction:
 	rra \ rra \ rra
 	or	b
 	ld	b, a
+	ld	a, d		; restore A
 	call	.getUp1
 	; now that's our MSB
 	jr	.spitMSB
-
-.spitRdK8:
-	call	.readR4
-	ret	nz
-	call	.placeRd
-	call	readComma
-	call	readWord
-	call	parseExpr
-	ret	nz
-	ld	a, c
-	ld	a, 0xff
-	call	.IX2A
-	ret	nz
-	push	af		; --> lvl 1
-	; let's start with the 4 lower bits
-	and	0xf
-	or	c
-	; We now have our LSB in A. Let's spit it now.
-	call	ioPutB
-	pop	af		; <-- lvl 1
-	; and now those high 4 bits
-	and	0xf0
-	rra \ rra \ rra \ rra
-	ld	b, a
-	call	.getUp1
-	jr	.spitMSB
-
-.spitRdBit:
-	call	.readR5
-	ret	nz
-	call	.placeRd
-	call	readComma
-	ret	nz
-	call	.readBit
-	ret	nz
-	; LSB is in A and is ready to go
-	call	ioPutB
-	call	.getUp1
-	jr	.spitMSB
-
 .spit:
 	; LSB is spit *before* MSB
 	inc	hl
@@ -380,8 +329,13 @@ parseInstruction:
 	; upcode becomes 0b111101
 	inc	b
 .rdBRBS:
-	call	.readBit
+	call	readWord
 	ret	nz
+	call	parseExpr
+	ld	a, 7
+	call	.IX2A
+	ret	nz
+	ld	c, a
 	call	readComma
 	ret	nz
 	jr	.spitBR2
@@ -395,30 +349,19 @@ parseInstruction:
 	ld	c, a
 	ret
 
-; Fetch a 8-bit upcode specified by instr index in D and set that upcode in HL
+; Fetch a 8-bit upcode specified by instr index in A and set that upcode in HL
 .getUp1:
-	ld	a, d
 	sub	I_ADC
 	ld	hl, instrUpMasks1
 	jp	addHL
 
-; Fetch a 16-bit upcode specified by instr index in D and set that upcode in HL
+; Fetch a 16-bit upcode specified by instr index in A and set that upcode in HL
 .getUp2:
-	ld	a, d
 	sub	I_BREAK
 	sla	a	; A * 2
 	ld	hl, instrUpMasks2
 	jp	addHL
 
-.readR4:
-	call	.readR5
-	ret	nz
-	; has to be in the 16-31 range
-	sub	0x10
-	jp	c, unsetZ
-	cp	a	; ensure Z
-	ret
-
 ; read a rXX argument and return register number in A.
 ; Set Z for success.
 .readR5:
@@ -433,18 +376,6 @@ parseInstruction:
 	ld	a, 31
 	jr	.IX2A
 
-.readBit:
-	call	readWord
-	ret	nz
-	call	parseExpr
-	ld	a, 7
-	call	.IX2A
-	ret	nz
-	or	c
-	ld	c, a
-	cp	a		; ensure Z
-	ret
-
 ; Put IX's LSB into A and, additionally, ensure that the new value is <=
 ; than what was previously in A.
 ; Z for success.

tools/tests/avra/test1.asm

@@ -7,5 +7,3 @@ breq bar
 asr r20
 bar:
 brbs 6, foo
-ori r22, 0x34+4
-sbrs r1, 3

tools/tests/avra/test1.expected

@@ -1 +1 @@
-<08><><EFBFBD><EFBFBD><EFBFBD>	<09>E<EFBFBD><45><EFBFBD>hc<13>
+<08><><EFBFBD><EFBFBD><EFBFBD>	<09>E<EFBFBD><45><EFBFBD>