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added uncond jp

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This commit is contained in:
Thorn Avery 2020-06-09 17:22:55 +12:00
parent 105fdc5b20
commit 2083300d70
2 changed files with 29 additions and 7 deletions
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18
README.md
View File

@ -5,17 +5,20 @@ very early days for now.
in the racket repl (comments for reader comprehension, remove before running):
```
(run-vm #x150 #x150 #x16 ; start-address, end-memory-view-addr, number-bytes-view
(run-vm #x150 #x150 #x19 ; start-address, end-memory-view-addr, number-bytes-view
'(#x3E #x69 ; LD A, $69
#x26 #x01 ; LD H, $01
#x2E #x62 ; LD L, $62
#x2E #x67 ; LD L, $67
#x77 ; LD (HL), A
#x2E #x5B ; LD L, $5B
#x36 #xE6 ; LD (HL), $E6 ($E6 is the opcode for XOR $xx)
#x10 ; STOP (this instruction @ address $015B)
#xF0 ; (non-instruction, will be arg for previous byte)
#x2E #x63 ; LD L, $63
#x2E #x68 ; LD L, $68
#x77 ; LD (HL), A
#xC3 #x64 #x01 ; JP $0164
#x10 ; STOP
#x7D ; LD A, L (address $0164)
#x10 ; STOP
))
```
@ -23,18 +26,19 @@ in the racket repl (comments for reader comprehension, remove before running):
will evaluate to:
```
PC: $0161, SP: $0000, Flags: %00000000
PC: $0166, SP: $0000, Flags: %00000000
BC: $0000, DE: $0000
HL: $0163, AF: $6000
HL: $0168, AF: $6800
(HL): $60
$0150 > $3e $69 $26 $01 $2e $62 $77 $2e $5b $36 $e6 $e6 $f0 $2e $63 $77 $10 $00 $69 $60 $00 $00 < $0165
$0150 > $3e $69 $26 $01 $2e $67 $77 $2e $5b $36 $e6 $e6 $f0 $2e $68 $77 $c3 $64 $01 $10 $7d $10 $00 $69 $60 < $0168
```
here we can see the program loaded starting from address `$0150`, including the `XOR` instruction loaded to `$015B` during execution, and the `$69` we loaded to memory, along with the result of `XOR $F0` we loaded to memory, at `$0162` and `$0163` respectively.
here we can see the program loaded starting from address `$0150`, including the `XOR` instruction loaded to `$015B` during execution, and the `$69` we loaded to memory, along with the result of `XOR $F0` we loaded to memory, at `$0167` and `$0168` respectively. we can also see that the `A` register is `$68`, the same as the `L` register, as the `JP` instruction executed properly and we skipped the `STOP` at address `$0163`.
## notes
currently supported instructions are:
* `JP #addr`
* `LD [reg], #imm`
* `LD [reg], [reg]`
* `XOR #imm`

18
vm.rkt
View File

@ -103,6 +103,14 @@
(cons (8b-ld-reg-imm y x)
(set-pc (add1pc pc) m))))
(define (make-jp cc m)
(letrec ([pc (mem-pc m)]
[y (get-byte pc m)]
[npc (add1pc pc)]
[x (get-byte npc m)]
[addr (make-16b-addr x y)])
(cons (jp cc addr) (set-pc npc m))))
(define (make-8b-ld-reg-reg y z m)
(cons (8b-ld-reg-reg y z)
m))
@ -123,6 +131,11 @@
(define (make-stop m)
(cons 'STOP m))
(define (jp cc addr)
(case cc
[(uncond) (jp-uncond addr)]
[else (nop)]))
(define (8b-ld-reg-imm reg imm)
(lambda (m)
(set-reg reg imm m)))
@ -133,6 +146,10 @@
(get-reg src m)
m)))
(define (jp-uncond addr)
(lambda (m)
(set-pc addr m)))
(define (8b-xor-imm imm)
(lambda (m)
(let ([a (bitwise-xor (get-reg 7 m)
@ -225,6 +242,7 @@
(cond
[(= #x00 op) (make-nop (set-pc npc m))]
[(= #x10 op) (make-stop (set-pc npc m))]
[(= #xC3 op) (make-jp 'uncond (set-pc npc m))]
[(= 1 x)
(make-8b-ld-reg-reg y z (set-pc npc m))]
[(and (= 3 x) (within z 4 6))