From a80c682d18d1f9da15cc5e28249194efc8e6afea Mon Sep 17 00:00:00 2001
From: kitty <nepeta@canaglie.net>
Date: Thu, 5 Mar 2026 00:38:19 +1100
Subject: move back to brk'd memory

someone on the uiua discord told me about mprotect. it worked!
---
 jefs.fs |  1 -
 jefs.s  | 33 +++++++++++++++++++++++++++++----
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/jefs.fs b/jefs.fs
index 45804c7..1d6d83b 100644
--- a/jefs.fs
+++ b/jefs.fs
@@ -1,7 +1,6 @@
 \ i think something is going on with the stack. i dunno
 \ things TODO:
 \ standardise stack comment abbrs (i like leo brodie's forth_style.txt)
-\ go back to brked user mem area (with mprotect) (someone in the uiua discord suggested it
 \ DO LOOP
 \ s\"
 \ add error handling to compiling words
diff --git a/jefs.s b/jefs.s
index 4050289..b58c691 100644
--- a/jefs.s
+++ b/jefs.s
@@ -81,6 +81,7 @@
 ;; syscall
 %assign	__NR_read	0
 %assign	__NR_write	1
+%assign __NR_mprotect	10
 %assign	__NR_brk	12
 %assign	__NR_exit	60
 ;; }}}
@@ -100,11 +101,36 @@ _start:
 	mov r14, wstack ; point SP to top
 	mov qword [rs0], rsp
 
+	call zero_here
+
 	call interpret
 	mov rdi, 0
 	mov rax, __NR_exit
 	syscall
 
+; i could separate this but i wanna have do in forth. euj
+defword "0here", zero_here, 0
+	; get current brk
+	xor rdi, rdi
+	mov rax, __NR_brk
+	syscall
+	mov qword [here], rax
+	mov qword [herestart], rax
+
+	; expand it to 640k
+	add rax, 0x9c400
+	mov rdi, rax
+	mov rax, __NR_brk
+	syscall
+	mov qword [heremax], rax
+
+	mov rdx, 0x7 ; PROT_EXEC | PROT_READ | PROT_WRITE
+	mov rsi, 0x9c400
+	mov rdi, qword [here]
+	mov rax, __NR_mprotect
+	syscall
+	ret
+
 defword "bye", bye, 0
 	mov rdi, 0
 	mov rax, __NR_exit
@@ -1177,14 +1203,13 @@ defvar "tib", tib, 0, initfile
 defvar "#tib", num_tib, 0, initlen
 defvar ">in", to_in, 0, 0
 defvar "state", state, 0, interpreting
-defvar "here", here, 0, umem
+defvar "here", here, 0, 0
 defvar "s0", s0, 0, wstack
-defvar "herestart", herestart, 0, umem ; beginning of user memory area
+defvar "herestart", herestart, 0, 0
 defvar "rs0", rs0, 0, 0
-defvar "heremax", heremax, 0, umem_e ; ending of user memory area
+defvar "heremax", heremax, 0, 0 ; ending of user memory area
 defvar "base", base, 0, 10
 defvar "error", error, 0, 0
-; defvar "handler", handler, 0, brac_handler
 defvalue "handler", handler, 0, brac_handler
 defvar "latest", latest, 0, lfa_latest
 
-- 
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