avra: add "with immediate" instructions

This commit is contained in:
Virgil Dupras 2019-12-14 09:05:38 -05:00
parent 4b9712a224
commit c696fcbce4
4 changed files with 79 additions and 6 deletions

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@ -178,4 +178,17 @@ 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

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@ -32,7 +32,7 @@ instrNames:
.equ I_BRBS 16
.db "BRBS", 0
.db "BRBC", 0
; Rd(5) + Rr(5)
; Rd(5) + Rr(5) (from here, instrUpMasks1)
.equ I_ADC 18
.db "ADC", 0
.db "ADD", 0
@ -47,8 +47,16 @@ instrNames:
.db "OR", 0
.db "SBC", 0
.db "SUB", 0
; no arg
.equ I_BREAK 31
.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
; no arg (from here, instrUpMasks2)
.equ I_BREAK 38
.db "BREAK", 0
.db "CLC", 0
.db "CLH", 0
@ -76,7 +84,7 @@ instrNames:
.db "SLEEP", 0
.db "WDR", 0
; Rd(5)
.equ I_ASR 57
.equ I_ASR 64
.db "ASR", 0
.db "COM", 0
.db "DEC", 0
@ -111,6 +119,14 @@ instrUpMasks1:
.db 0b00101000 ; OR
.db 0b00001000 ; SBC
.db 0b00011000 ; SUB
; Rd(5) + 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
; 16-bit constant masks associated with each instruction. In the same order as
; in instrNames
@ -217,8 +233,10 @@ parseInstruction:
ld bc, 0
cp I_ADC
jp c, .BR
cp I_BREAK
cp I_ANDI
jr c, .spitRd5Rr5
cp I_BREAK
jr c, .spitRdK8
cp I_ASR
jr c, .spitNoArg
; spitRd5
@ -231,6 +249,7 @@ parseInstruction:
.spitNoArg:
call .getUp2
jr .spit
.spitRd5Rr5:
ld d, a ; save A for later
call .readR5
@ -255,6 +274,36 @@ parseInstruction:
call .getUp1
; now that's our MSB
jr .spitMSB
.spitRdK8:
ld d, a ; save A for later
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
ld a, d ; restore A
call .getUp1
; now that's our MSB
jr .spitMSB
.spit:
; LSB is spit *before* MSB
inc hl
@ -362,6 +411,15 @@ parseInstruction:
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:
@ -376,6 +434,7 @@ parseInstruction:
ld a, 31
jr .IX2A
; Put IX's LSB into A and, additionally, ensure that the new value is <=
; than what was previously in A.
; Z for success.

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

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