error handling?

3 files changed, 44 insertions, 7 deletions

diff --git a/jefs.fs b/jefs.fs
index 9677229..e056cf7 100644
--- a/jefs.fs
+++ b/jefs.fs
@@ -165,11 +165,12 @@ variable hld
 \ : .free  bytes-free u. ." of " bytes-allocated u. ." bytes free (used " bytes-used (.) say ." )" cr ; \ segfaults
 
 : >nfa ( lfa -- nfa )  9 + ;
-: (words) ( lfa -- )  >nfa dup w@ swap 1+ 1+ swap say 2 spaces ; \ TODO works? maybe? idk
-: words  latest @ begin ?dup 0<> while dup (words) @ ( todo ->NEXT ) repeat cr ;
+: >ffa ( lfa -- ffa )  8 + ;
+: (words) ( lfa -- )  >nfa dup w@ swap 2 + swap say 2 spaces ;
+: words  latest @ begin ?dup 0<> while dup (words) @ repeat cr ;
 
 \ .free bye
-\ : t s" eue eu eo o eu" drop .s say s" eue " ;
+\ : t s" eue eu eo o eu" ; \ s" eue " [ HEREDUMP ] ;
 
-words
+\ words
 bye
diff --git a/jefs.s b/jefs.s
index 3d9fa1c..f3900f8 100644
--- a/jefs.s
+++ b/jefs.s
@@ -6,9 +6,18 @@
 	mov qword [r14], %1
 %endmacro
 
+; this feels like Too much code and probably Too slow to have for every pspop.
+; we'll see
+; clobbers r8 (which isn't actually used anywhere here)
 %macro pspop 1
 	mov %1, qword [r14]
 	lea r14, [r14+8]
+	cmp r14, wstack
+	jle %%ok
+	mov qword [error], 1
+	mov r8, qword [handler]
+	call r8
+	%%ok:
 %endmacro
 
 ;;; dictionary macros {{{
@@ -62,7 +71,7 @@
 
 section .bss exec
 wstack_b:	resq 2047
-wstack:		resq 1
+wstack:		resq 2
 
 umem:	resb 0x9c400
 umem_e:
@@ -174,11 +183,13 @@ defword "c,", c_comma, 0
 	ret
 
 defword "cmove", _cmove, 0 ; ( a1 a2 u -- )
+	call heredump
 	pspop rcx
 	pspop rdi
 	pspop rsi
 
 	rep movsb
+	call heredump
 	ret
 
 defword "cmove,", _cmove_comma, 0 ; ( c-addr u -- )
@@ -242,6 +253,8 @@ defword "parse", parse, 0
 	pspush r11 ; u
 	ret
 
+; segfault issue is in here i think?
+; on second go around only one value is returned?
 defword "cparse", cparse, 0
 	pspop r15 ; c
 	mov r13, qword [to_in]
@@ -1023,6 +1036,18 @@ defword "0branch", zerobranch, 0
 	mov qword [here], r12
 	ret
 
+; rudimentary error handler
+; this word may be called when the stack is fucked,
+; so instead we take the error from a variable called error.
+; this word is intended to be called as an xt from the HANDLER variable,
+; so better error handling can be given from forth.
+defword "(handler)", brac_handler, 0
+	mov r11, [error]
+	mov rdi, r11
+	mov rax, __NR_exit
+	syscall
+	ret
+
 ; TEMPORARY HORRIBLE DEBUGGING BULLSHIT {{{
 ; debugging word; outputs raw bytes so needs to be piped through `x(x)d`
 ; terrible and awful
@@ -1100,6 +1125,8 @@ defvar "s0", s0, 0, wstack
 defvar "h0", h0, 0, umem ; beginning of user memory area
 defvar "hend", hend, 0, umem_e ; ending of user memory area
 defvar "base", base, 0, 10
+defvar "error", error, 0, 0
+defvar "handler", handler, 0, brac_handler
 defvar "latest", latest, 0, lfa_latest
 
 initfile:
diff --git a/readme.md b/readme.md
index 7f34a62..e7c84be 100644
--- a/readme.md
+++ b/readme.md
@@ -69,8 +69,17 @@ maybe this sucks shit but my idea is that i compile in a relative jmp with
 
 ### PNO
 'pictured numeric output'. its forth's numeric output functionality.
-this is me trying to describe it so i can figure it out and implement it.
 note that this forth doesn't have double numbers
 (i don't think it's necessary, since cells are 64 bit)
 so PNO works on single cell values.
-PNO is started by `<#` and ended by `#>`.
+
+### error codes
+in order to have Good Error Handling anywhere, the error handler's xt
+is stored in the `handler` variable and is then called by loading its value
+and `execute`ing it. the actual description of the error comes from the
+`error` variable (in case the stack is fucked)
+
+the error codes are:
+
+- 0: nothing.
+- 1: stack underflow