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avra: add "with immediate" instructions
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@ -178,4 +178,17 @@ arguments are separated by commas.
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To assemble an AVR assembler, use the `gluea.asm` file instead of the regular
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one.
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Note about AVR and PC: In most assemblers, arithmetics for instructions
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addresses have words (two bytes) as their basic unit because AVR instructions
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are either 16bit in length or 32bit in length. All addresses constants in
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upcodes are in words. However, in zasm's core logic, PC is in bytes (because z80
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upcodes can be 1 byte).
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The AVR assembler, of course, correctly translates byte PCs to words when
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writing upcodes, however, when you write your expressions, you need to remember
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to treat with bytes. For example, in a traditional AVR assembler, jumping to
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the instruction after the "foo" label would be "rjmp foo+1". In zasm, it's
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"rjmp foo+2". If your expression results in an odd number, the low bit of your
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number will be ignored.
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[libz80]: https://github.com/ggambetta/libz80
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@ -32,7 +32,7 @@ instrNames:
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.equ I_BRBS 16
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.db "BRBS", 0
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.db "BRBC", 0
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; Rd(5) + Rr(5)
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; Rd(5) + Rr(5) (from here, instrUpMasks1)
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.equ I_ADC 18
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.db "ADC", 0
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.db "ADD", 0
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@ -47,8 +47,16 @@ instrNames:
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.db "OR", 0
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.db "SBC", 0
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.db "SUB", 0
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; no arg
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.equ I_BREAK 31
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.equ I_ANDI 31
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.db "ANDI", 0
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.db "CPI", 0
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.db "LDI", 0
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.db "ORI", 0
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.db "SBCI", 0
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.db "SBR", 0
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.db "SUBI", 0
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; no arg (from here, instrUpMasks2)
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.equ I_BREAK 38
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.db "BREAK", 0
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.db "CLC", 0
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.db "CLH", 0
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@ -76,7 +84,7 @@ instrNames:
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.db "SLEEP", 0
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.db "WDR", 0
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; Rd(5)
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.equ I_ASR 57
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.equ I_ASR 64
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.db "ASR", 0
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.db "COM", 0
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.db "DEC", 0
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@ -111,6 +119,14 @@ instrUpMasks1:
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.db 0b00101000 ; OR
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.db 0b00001000 ; SBC
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.db 0b00011000 ; SUB
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; Rd(5) + K(8): XXXXKKKK ddddKKKK
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.db 0b01110000 ; ANDI
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.db 0b00110000 ; CPI
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.db 0b11100000 ; LDI
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.db 0b01100000 ; ORI
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.db 0b01000000 ; SBCI
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.db 0b01100000 ; SBR
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.db 0b01010000 ; SUBI
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; 16-bit constant masks associated with each instruction. In the same order as
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; in instrNames
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@ -217,8 +233,10 @@ parseInstruction:
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ld bc, 0
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cp I_ADC
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jp c, .BR
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cp I_BREAK
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cp I_ANDI
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jr c, .spitRd5Rr5
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cp I_BREAK
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jr c, .spitRdK8
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cp I_ASR
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jr c, .spitNoArg
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; spitRd5
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@ -231,6 +249,7 @@ parseInstruction:
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.spitNoArg:
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call .getUp2
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jr .spit
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.spitRd5Rr5:
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ld d, a ; save A for later
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call .readR5
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@ -255,6 +274,36 @@ parseInstruction:
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call .getUp1
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; now that's our MSB
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jr .spitMSB
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.spitRdK8:
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ld d, a ; save A for later
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call .readR4
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ret nz
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call .placeRd
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call readComma
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call readWord
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call parseExpr
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ret nz
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ld a, c
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ld a, 0xff
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call .IX2A
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ret nz
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push af ; --> lvl 1
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; let's start with the 4 lower bits
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and 0xf
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or c
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; We now have our LSB in A. Let's spit it now.
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call ioPutB
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pop af ; <-- lvl 1
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; and now those high 4 bits
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and 0xf0
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rra \ rra \ rra \ rra
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ld b, a
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ld a, d ; restore A
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call .getUp1
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; now that's our MSB
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jr .spitMSB
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.spit:
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; LSB is spit *before* MSB
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inc hl
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@ -362,6 +411,15 @@ parseInstruction:
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ld hl, instrUpMasks2
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jp addHL
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.readR4:
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call .readR5
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ret nz
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; has to be in the 16-31 range
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sub 0x10
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jp c, unsetZ
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cp a ; ensure Z
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ret
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; read a rXX argument and return register number in A.
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; Set Z for success.
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.readR5:
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@ -376,6 +434,7 @@ parseInstruction:
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ld a, 31
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jr .IX2A
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; Put IX's LSB into A and, additionally, ensure that the new value is <=
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; than what was previously in A.
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; Z for success.
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@ -7,3 +7,4 @@ breq bar
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asr r20
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bar:
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brbs 6, foo
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ori r22, 0x34+4
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@ -1 +1 @@
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<08><><EFBFBD><EFBFBD><EFBFBD> <09>E<EFBFBD><45><EFBFBD>
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<08><><EFBFBD><EFBFBD><EFBFBD> <09>E<EFBFBD><45><EFBFBD>hc
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