From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Tue, 15 Jun 2021 04:29:48 +0000 (+1000)
Subject: introduced a hold area for temp space
X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=6234f75b32f6113896d6b15c79fb29d5c7ccb79c;p=rrq%2Frrqforth.git

introduced a hold area for temp space
---

diff --git a/adoc/p_tempheld.adoc b/adoc/p_tempheld.adoc
new file mode 100644
index 0000000..4233b2c
--- /dev/null
+++ b/adoc/p_tempheld.adoc
@@ -0,0 +1,15 @@
+// temp.asm:	WORD p_tempheld,'TEMPHELD',dovariable
+
+anchor:p_tempheld[]
+
+=== Word: TEMPHELD
+
+....
+Data stack: ( -- a )
+....
+
+"TEMPHELD" is a variable word that keeps the lowest offset of the
+<<p__tempspace,TEMPSPACE>> space to reuse upon cycling. The space
+below TEMPHELD is "held" in the sense of not being reused upon
+cycling. An application may change the TEMPSPACE offset as needed to
+dynamically preserve memory longer term.
diff --git a/reference.adoc b/reference.adoc
index 1d9f60e..e48dbd7 100644
--- a/reference.adoc
+++ b/reference.adoc
@@ -293,6 +293,8 @@ include::adoc/p_tell.adoc[]
 include::separator.adoc[]
 include::adoc/p_temp.adoc[]
 include::separator.adoc[]
+include::adoc/p_tempheld.adoc[]
+include::separator.adoc[]
 include::adoc/p_tempspace.adoc[]
 include::separator.adoc[]
 include::adoc/p_terminate0.adoc[]
diff --git a/temp.asm b/temp.asm
index 8e0be25..7ece590 100644
--- a/temp.asm
+++ b/temp.asm
@@ -1,16 +1,23 @@
-;;; Managing a memory area for temporary objects
-;;;
-;;; A temporary object space is allocated from the current usage
-;;; level, or cycling back to be from the lowest space address when
-;;; the requested size exceeds the space edge.
+;;; Managing a memory area for temporary "objects".
 ;;;
+;;; Object space is allocated cyclically, starting subsequent to prior
+;;; allocation and cycling back when requested object size exceeds
+;;; the space edge. The "inital" part, which starts as empty, is
+;;; considered "held" space that is not reused when cycling back, and
+;;; apart from allowing for this, the space management is left open.
+
 
 	WORD p_objectspace,'TEMPSPACE',dovariable
 	;; Holds size and address of the object space.
-	dq 104857600 ; [0] Total object space size (request size)
-	dq 0 ; [8] Object space base address
+	dq 1073741824 ; [0] Total object space size (request size)
+	dq 0 ; [8] Object space base address.
 	dq 0 ; [16] Currently used.
 
+	WORD p_tempheld,'TEMPHELD',dovariable
+	;; ( -- a )
+	;; Marks the barrier for "held space"
+	dq 0 ; [24] Currently held.
+
 	WORD p_temp,'TEMP',fasm
 	;; ( size -- addr )
 	;; Allocate an object of given size
@@ -26,14 +33,15 @@ p_objecthole_initialized:
 	add rax,qword [p_objectspace_DFA+16]
 	cmp rax,qword [p_objectspace_DFA]
 	jl p_objecthole_from_tail
-	mov qword [p_objectspace_DFA+16],0
-	mov rax,qword [rsp]
+	mov rax,qword [p_tempheld_DFA] ; cycling back to here
+	mov qword [p_objectspace_DFA+16],rax
+	add rax,qword [rsp]
 p_objecthole_from_tail:
 	;; rax = new usage count
 	mov rbx,qword [p_objectspace_DFA+16]
-	mov qword [p_objectspace_DFA+16],rax
 	add rbx,qword [p_objectspace_DFA+8]
 	mov qword [rsp],rbx
+	mov qword [p_objectspace_DFA+16],rax
 	popr rsi
 	next
 
diff --git a/wordindex.adoc b/wordindex.adoc
index e59bfaa..c30b9bf 100644
--- a/wordindex.adoc
+++ b/wordindex.adoc
@@ -167,6 +167,7 @@ xref:p_system[SYSTEM] {nbsp}
 xref:p_tell[TELL] {nbsp}
 xref:p_dot_temp[.TEMP] {nbsp}
 xref:p_temp.adoc[TEMP] {nbsp}
+xref:p_tempheld.adoc[TEMPHELD] {nbsp}
 xref:p_tempspace[TEMPSPACE] {nbsp}
 xref:p_terminate0[TERMINATE0] {nbsp}
 xref:p_tfa2cfa[TFA>CFA] {nbsp}