DEFER-ed words in core, file open/read/write/close

3 files changed, 68 insertions, 2 deletions

diff --git a/readme.md b/readme.md
index 0b89015..73af8a2 100644
--- a/readme.md
+++ b/readme.md
@@ -8,6 +8,7 @@ documentation and will be obvious or documented in the description.
 
 - `a`: memory address
 - `c`: one byte value
+- `e`: error code
 - `n`: signed integer
 - `u`: unsigned integer
 - `z`: null-terminated string
@@ -63,6 +64,11 @@ which simply pushes the address following the definition to the stack.
 this messes with the return stack and is not meant to be called
 outside of its specific context.
 
+### `(defer)   ( -- )`
+activate a deferred word from the address following this word's call.
+this messes with the return stack and is not meant to be called
+outside of its specific context.
+
 ### `(does>)   ( -- )`
 run non-default behaviour of a `create`d word.
 pushes the data location onto the stack and calls the word
@@ -171,6 +177,13 @@ return true if n1 is greater than or equal to n2.
 ### `>body   ( ht -- xt )`
 yield the code field of header token.
 
+### `>errno   ( u -- val err )`
+transform the result of a system call into a value/error pair.
+if no error occured, err is zero and val is the result,
+if an error has occurred, val is zero and
+err is a negative integer
+(the exact value depends on the error)
+
 ### `>in   ( -- a )`
 variable containing the index of the first unparsed character
 in the input buffer.
@@ -283,6 +296,9 @@ transform an amount of cells into an amount of bytes.
 ### `char   ( "c" -- c )`
 yield the value of the first character of the next word in the input stream.
 
+### `close-file   ( fd -- e )`
+close the file at fd.
+
 ### `cmove   ( a1 a2 u -- )`
 copy u bytes of memory from a1 to a2.
 bytes are copied in low memory to high memory order.
@@ -434,6 +450,11 @@ and no number is provided.
 ### `octal   ( -- )`
 set current base to octal.
 
+### `open-file   ( z mode -- fd e )`
+open the given file with the given mode (probably r/w, r/o or w/o)
+and yield the resulting file descriptor
+note that this word uses the pad.
+
 ### `or  ( u1 u2 -- u )`
 perform bitwise OR on u1 and u2.
 
@@ -487,6 +508,10 @@ move a value from the return stack to the working stack.
 ### `rdrop   ( R: u -- )`
 remove the value at the top of the return stack.
 
+### `read-file   ( a u fd -- u' e )`
+read u bytes from fd into memory location a.
+u' is the number of bytes read.
+
 ### `repeat   ( -- ) IMMEDIATE COMPILE-ONLY`
 in a begin-while-repeat loop, loop back to the condition.
 
@@ -637,6 +662,10 @@ a constant, meaning 'write only', used for file I/O.
 if given flag is true, continue the current begin-while-repeat loop,
 otherwise branch to after.
 
+### `write-file   ( a u fd -- u' e )`
+write u bytes from a into fd.
+u' is the number of bytes written.
+
 ### `xor   ( u1 u2 -- u )`
 perform bitwise XOR on u1 and u2.
 
diff --git a/sanctuary.fs b/sanctuary.fs
index 1aab4e2..e198710 100644
--- a/sanctuary.fs
+++ b/sanctuary.fs
@@ -74,6 +74,7 @@ decimal
 	r> dup >resolve 4 + ( u a )
 	postpone literal ( a ) drop ; immediate compile-only
 : zstrlen  dup begin dup c@ 0<> while 1+ repeat swap - ;
+\ todo s>z becomes s>z, s>z writes to pad (will then need to be moved below pno)
 : s>z  here -rot cmove, 0 c, ;
 
 \ PRIVATISATION AND HIDING {{{
@@ -126,6 +127,12 @@ variable hld
 : #>  drop hld @ pad$ over - ;
 \ }}}
 
+\ ERRNO {{{
+\ transform syscall result into [RESULT] IOR output,
+\ where IOR is zero on no error and negative on an error (RESULT then being 0)
+: >errno  dup 0< if 0 swap else 0 then ;
+\ }}}
+
 \ I/O {{{
 0 constant stdin
 1 constant stdout
@@ -142,6 +149,11 @@ variable hld
 0 constant r/o
 1 constant w/o
 2 constant r/w
+
+: open-file  swap >r 0 r> sys-open >errno ;
+: close-file  sys-close ;
+: read-file  >r swap r> sys-read >errno ;
+: write-file  >r swap r> sys-write >errno ;
 \ }}}
 
 bye
diff --git a/sanctuary.s b/sanctuary.s
index d37ca5a..02fb961 100644
--- a/sanctuary.s
+++ b/sanctuary.s
@@ -40,6 +40,14 @@
 	%2:
 %endmacro
 
+%macro defdefer 3
+	defcode %1, %2, %3
+	mov r11, dodefer
+	call r11
+	dq do_%2
+	do_%2:
+%endmacro
+
 ; this is just taken from jewelforth, and does not correspond
 ; to how user variables are planned to work in sanctuary
 ; so todo make better later? i don't know if it really matters
@@ -50,6 +58,17 @@
 	pspush qword %2
 	ret
 %endmacro
+
+%macro defdefervar 4
+	%2: dq %4
+	defdict %1, %2, %3
+	mov r11, dodefer
+	call r11
+	dq do_%2
+	do_%2:
+	pspush qword %2
+	ret
+%endmacro
 ; }}}
 
 %assign smudge_mask	0x1
@@ -258,7 +277,7 @@ defcode "parse", parse, 0
 ; r11: input addr
 ; r12: pointer into currently processing word
 ; r13: same as r12 but kept at xt
-defcode "find", find, 0
+defdefer "find", find, 0
 	pspop r10 ; u
 	pspop r11 ; a
 	mov r12, qword [latest]
@@ -1124,6 +1143,12 @@ defcode "(does>)", dodoes, 0
 	jmp r12
 	; no RET
 
+defcode "(defer)", dodefer, 0
+	pop r11
+	mov r12, [r11]
+	jmp r12
+	; also no RET
+
 ; TEMPORARY WONKY DEBUGGING FUNCTIONS {{{
 ; .s {{{
 defcode ".s", dots, 0
@@ -1184,7 +1209,7 @@ defvar "tib", tib, 0, initfile
 defvar "#tib", n_tib, 0, initlen
 defvar ">in", to_in, 0, 0
 defvar "handler", handler, 0, do_0handler
-defvar "latest", latest, 0, lfa_latest
+defdefervar "latest", latest, 0, lfa_latest
 
 initfile: incbin "sanctuary.fs"
 initlen equ $ - initfile