1 files changed, 34 insertions(+), 15 deletions(-)

M onward.s

@@ 3,32 3,27 @@ use64
 format ELF64
 public start as '_start'
 
+; RSP = data stack
+; RSI = virtual instruction stream
+
 ;; system calls
 SYS_WRITE = 1
 SYS_EXIT = 60
 
+;; standard file handles
 STDIN = 0
 STDOUT = 1
 
-;;;
-
-ADDR_SIZE = 8             ; addr size in bytes
+;;
 
-macro dstack { rsp }      ; data stack
-; rsi points to virtual instructions
+ADDR_SIZE = 8
 
 macro defcode name {
-    public l_#name
-l_#name:
-    ;dd link
-    ;set link, name_#label
-    ;mstr db `name
     align ADDR_SIZE
 name:
 }
 
-; ASMWORD = array of instructions (aka a label)
-
+;; push/pop data stack
 macro pushd r {
     lea rsp, [rsp + ADDR_SIZE]
     mov [rsp], r


@@ 39,9 34,9 @@ macro popd r {
     lea rsp, [rsp - ADDR_SIZE]
 }
 
+;; interpret next instruction pointed to by RSI
 macro next {
-    ; rsi has type ASMWORD*;
-    mov rax, qword [rsi] ; rax = ASMWORD[0] (or *ASMWORD)
+    mov rax, qword [rsi]
     lea rsi, [rsi + ADDR_SIZE]
     jmp qword rax
 }


@@ 94,6 89,31 @@ section '.text' ; readable executable
     mov rsi, r8 ; restore rsi
     next
 
+    defcode mstore
+    popd rbx ; addr to store at
+    popd rax ; value to store at addr
+    mov [rbx], rax
+    next
+
+    defcode mfetch
+    popd rbx
+    mov rax, [rbx]
+    pushd rax
+    next
+
+    defcode mstoreb
+    popd rbx
+    popd rax
+    mov [ebx], byte al
+    next
+
+    defcode mfetchb
+    popd rbx
+    xor rax, rax
+    mov al, byte [ebx]
+    pushd rax
+    next
+
     defcode exit
     mov rax, SYS_EXIT
     mov rdi, 0


@@ 113,4 133,3 @@ instrs:
     dq emit
     dq branch, -32
     dq exit
-