From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Tue, 18 May 2021 12:19:48 +0000 (+1000)
Subject: Change word layout to more wasteful use of full cells.
X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=3025dcd6895d494d9f5e700887033f2c315e06d2;p=rrq%2Frrqforth.git

Change word layout to more wasteful use of full cells.
Also added cross-pointers to simplify moving between tfa and cfa.
---

diff --git a/machine.asm b/machine.asm
index a8bfbd8..74b1060 100644
--- a/machine.asm
+++ b/machine.asm
@@ -103,30 +103,49 @@ macro DOFORTH 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 {
+;;; ========================================
+;;; Macro WORD starts a FORTH word definition in this code.
+;;; The layout of a word is as follows:
+;;; TFA: [8 bytes] pointer to previous word in the word list
+;;;      [8 bytes] pointer to the word's CFA
+;;;      [8 bytes] a flags field
+;;;      [8 bytes] the length of the word's pname
+;;;      [varying] the word's pname
+;;;      [1 byte]  NUL -- making an asciiz of the pname
+;;;      ;;[? bytes] 0-7 bytes for address alignment to [disabled]
+;;;      [8 bytes] pointer to the word's TFA
+;;; OFF: [8 bytes] the DOES offset for the word
+;;; CFA: [8 bytes] pointer to the word's "doer" code
+;;; DFA: [? bytes] the word's data field
+
+macro WORD label, name, doer, flags, previous, offset {
+	local pname
 	;; align 8
 label#_TFA:
 	;; TFA
-	dq previous_word
+	if previous eq
+	    dq previous_word
+	else
+	    dq previous
+	end if
 	previous_word = label#_TFA
 	;; PFA
+	dq label#_CFA		; link to CFA of word
+	dq flags + 0
 label#_PFA:
-	db flags + 0
-	db label - $ - 2
+	dq pname - $ - 8
 	db name
-	db 0
+pname:  db 0			; extra NUL byte
 	;; align 8
-
+	dq label#_TFA		; link to TFA of word
 label#_OFF:
-	dq 0			; The DOES offset. Defaults to 0.
+	dq offset + 0		; The DOES offset. Defaults to 0.
 	;; also CFA = pointer to "doer"
+label#_CFA:
 label:
 	if doer eq
 	    dq doforth
@@ -141,6 +160,39 @@ label:
 label#_DFA:
 }
 
+macro tfa2cfa reg {
+	mov reg,qword [reg+8]
+}
+macro tfa2dfa reg {
+	tfa2cfa reg
+	add reg,8
+}
+macro tfa2pfa reg {
+	add reg,24
+}
+macro tfa2pname reg {
+	add reg,32
+}
+macro cfa2tfa reg {
+	sub reg,16
+	mov reg,qword [reg]
+}
+macro cfa2dfa reg {
+	add reg,8
+}
+macro dfa2cfa reg {
+	sub reg,8
+}
+macro dfa2tfa reg {
+	sub reg,24
+	mov reg,qword [reg]
+}
+macro pushpname rg { 	; ( reg -- chars* length )
+	add rg,8
+	push rg
+	sub rg,8
+	push qword [rg]
+}
 ;;; ========================================
 ;;; The BLOCK macro lays out the length for a subsequent block to the
 ;;; given label.
@@ -151,11 +203,12 @@ datastart:
 	}
 
 ;;; ========================================
-;;; The STRING macro lays out length byte and data for s short string
+;;; The STRING macro lays out length cell and data for several string
+;;; components.
 macro STRING [data] {
 common
 	local datastart, dataend
-	db dataend - datastart
+	dq dataend - datastart
 datastart:
 forward
 	db data