added WORDS

[rrq/rrqforth.git] / machine.asm

diff --git a/machine.asm b/machine.asm
index ddfb9711fe18abd89b514d3ccffd2989a18140c8..a8bfbd8f7652985a63836f81a38165211ec5efbb 100644 (file)
--- a/machine.asm
+++ b/machine.asm
@@ -42,6 +42,124 @@
 ;;; clobbers rdi rsi rdx rcx r8 r9 r11
 ;;; rax = syscall id
 ;;;
-;;; function calling
 
+;;; ######################################################################
+
+;;; ============================================================
+;;; FORTH machine model
+;;; rsp = data stack pointer
+;;; rbp = return stack pointer
+;;; rsi = instruction pointer
+
+;;; ========================================
+;;; The pushr macro pushes x onto the return stack
+;;; The popr macro pops x from the return stack
+macro pushr x {
+       sub rbp, 8
+       mov [rbp], x
+}
+
+macro popr x {
+       mov x, [rbp]
+       add rbp, 8
+}
+
+;;; ========================================
+;;; The next macro "moves" execution to the next FORTH instruction,
+;;; using rsi as instruction pointer. It points to the doer field of a
+;;; word, which points to the assembly code that implements the
+;;; execution effect of the word. That doer code is entered with rsi
+;;; referring to the subsequent address in the colling word, and rax
+;;; referring to the doer field of the called word.
+
+macro next {
+       lodsq                   ; mov rax, [rsi] + add rsi,8
+       jmp qword [rax]         ; goto code of that FORTH word (64 bit jump)
+}
+
+;;; ========================================
+;;; The FORTH macro transitions to inline FORTH execution.
+macro FORTH {
+       local forthcode
+       mov rsi,forthcode
+       next
+       ;; align 8
+forthcode:
+}
+
+;;; ========================================
+;;; The ENDFORTH macro transitions back to inline assembler after FORTH
+
+macro ENDFORTH {
+       dq inline_code
+}
+
+;;; ========================================
+;;; The DOFORTH lays out a single FORTH call
+
+macro DOFORTH label {
+       FORTH
+       dq label
+       ENDFORTH
+}
+
+;;; ========================================
+;;; Macro WORD starts a FORTH word definition in this code
+;;; 
+       previous_word = 0       ; Used for chaining the words
+
+       IMMEDIATE = 1           ; optional flag (symbol)
+
+macro WORD label, name, doer, flags {
+       ;; align 8
+label#_TFA:
+       ;; TFA
+       dq previous_word
+       previous_word = label#_TFA
+       ;; PFA
+label#_PFA:
+       db flags + 0
+       db label - $ - 2
+       db name
+       db 0
+       ;; align 8
+
+label#_OFF:
+       dq 0                    ; The DOES offset. Defaults to 0.
+       ;; also CFA = pointer to "doer"
+label:
+       if doer eq
+           dq doforth
+       else
+           if doer in <fasm>
+               dq label#_DFA
+           else
+               dq doer
+           end if
+       end if
+       ;; DFA
+label#_DFA:
+}
+
+;;; ========================================
+;;; The BLOCK macro lays out the length for a subsequent block to the
+;;; given label.
+macro BLOCK endlabel {
+       local datastart
+       dq endlabel - datastart
+datastart:
+       }
+
+;;; ========================================
+;;; The STRING macro lays out length byte and data for s short string
+macro STRING [data] {
+common
+       local datastart, dataend
+       db dataend - datastart
+datastart:
+forward
+       db data
+common
+dataend:
+       }