1 files changed, 109 insertions(+), 29 deletions(-)

M onward.s

@@ 3,10 3,12 @@ use64
 format ELF64
 public start as '_start'
 
-; RSP = data stack
+; RSP = return stack
+; RBP = data stack
 ; RSI = virtual instruction stream
 
 ;; system calls
+SYS_READ = 0
 SYS_WRITE = 1
 SYS_EXIT = 60
 


@@ 14,30 16,35 @@ SYS_EXIT = 60
 STDIN = 0
 STDOUT = 1
 
+DEBUG = 1
+
 ;;
 
 ADDR_SIZE = 8
 
 macro defcode name {
-    align ADDR_SIZE
+    public name
+    align ADDR_SIZE ; not sure if i need this
 name:
 }
 
 macro defword wordname {
-    align ADDR_SIZE
+    public wordname
+    align ADDR_SIZE ; or this...
 wordname:
     jmp docol
 }
 
 ;; push/pop data stack
 macro pushd r {
-    lea rsp, [rsp + ADDR_SIZE]
-    mov [rsp], r
+    lea rbp, [rbp + ADDR_SIZE]
+    mov [rbp], r
 }
 
+; TODO: add safety check
 macro popd r {
-    mov r, [rsp]
-    lea rsp, [rsp - ADDR_SIZE]
+    mov r, [rbp]
+    lea rbp, [rbp - ADDR_SIZE]
 }
 
 ;; interpret next instruction pointed to by RSI


@@ 49,7 56,9 @@ macro next {
 
 IMMEDIATE = 0
 COMPILE = 1
-var_STATE: db IMMEDIATE
+STATE: db IMMEDIATE
+
+KEY: db 0
 
 section '.text' ; readable executable
 


@@ 59,97 68,168 @@ docol:
     mov rsi, rax
     next
 
-    defcode drop
+defcode drop
     popd rax
     next
 
-    defcode exitword
+defcode exitword
     pop rsi
     next
 
-    defcode swap
+defcode swap
     popd rax
     popd rbx
     pushd rbx
     pushd rax
     next
 
-    defcode sdup
+defcode sdup
     popd rax
     pushd rax
     pushd rax
     next
 
-    defcode lit
+defcode lit
     mov rax, [rsi]
     pushd rax
     lea rsi, [rsi + ADDR_SIZE]
     next
 
-    defcode lbrac
-    mov [var_STATE], byte IMMEDIATE
+defcode lbrac
+    mov [STATE], byte IMMEDIATE
     next
 
-    defcode rbrac
-    mov [var_STATE], byte COMPILE
+defcode rbrac
+    mov [STATE], byte COMPILE
     next
 
-    defcode emit
+defcode emit
     mov r8, rsi ; backup rsi since we'll clobber it
     mov rax, SYS_WRITE
     mov rdi, STDOUT
-    lea rsi, [rsp]
+    lea rsi, [rbp]
     mov rdx, 1
     syscall
     popd rax
     mov rsi, r8 ; restore rsi
     next
 
-    defcode mstore
+defcode mstore
     popd rbx ; addr to store at
     popd rax ; value to store at addr
     mov [rbx], rax
     next
 
-    defcode mfetch
+defcode mfetch
     popd rbx
     mov rax, [rbx]
     pushd rax
     next
 
-    defcode mstoreb
+defcode mstoreb
     popd rbx
     popd rax
     mov [ebx], byte al
     next
 
-    defcode mfetchb
+defcode mfetchb
     popd rbx
     xor rax, rax
     mov al, byte [ebx]
     pushd rax
     next
 
-    defcode exit
+defcode exit ; clean exit
     mov rax, SYS_EXIT
     mov rdi, 0
     syscall
 
-    defcode branch
+defcode exit2 ; exit with error code
+    mov rax, SYS_EXIT
+    popd rdi
+    syscall
+
+defcode branch
+    add esi, [esi]
+    next
+
+; TODO: make this more compact
+defcode zbranch ; 0BRANCH
+    popd rax
+    cmp rax, 0
+    jnz continue
     add esi, [esi]
     next
+continue:
+    lea esi, [esi + ADDR_SIZE]
+    next
+
+defcode equa
+    popd rax
+    popd rbx
+    cmp rax, rbx
+    sete al
+    pushd rax
+    next
+
+defcode key
+    mov r8, rsi ; backup rsi since we'll clobber it
+    mov rax, SYS_READ
+    mov rdi, STDIN
+    mov rsi, KEY
+    mov rdx, 1
+    syscall
+    mov rsi, r8 ; restore rsi
+
+    cmp rdx, 0 ; exit if ^D (zero length string)
+    jz exit
+
+    mov al, byte [KEY]
+    pushd rax
+    next
+
+defcode inv ; not
+    popd rax
+    test rax, rax
+    je tru
+    mov rax, 0
+    pushd rax
+    next
+tru:
+    mov rax, 1
+    pushd rax
+    next
+
+defword getword ; : WORD ( -- wordlen chars ... ) KEY DUP ' ' = 0BRANCH -48 ;
+    dq key
+    dq sdup
+    dq lit, ' '
+    dq equa
+    dq zbranch, -48
+    dq drop
+    dq drop
+    dq exitword
 
-    defword starloop
+; a little test word
+defword starloop
     dq lit, '*'
     dq emit
     dq branch, -32
     dq exitword
 
+defword atest
+    dq lit, '*'
+    dq lit, 'a'
+    dq emit
+    dq exitword
+
 start:
-    cld
+    mov rbp, rsp ; allocate data stack
+    add rsp, ADDR_SIZE * 256 ; make it 256 words
     mov rsi, instrs
     next
 
 instrs:
-    dq starloop
-    dq exit
+    dq getword
+    dq getword
+    dq exit2