Fixed lisp's behavior when there is insufficient memory

CHANGELOG.org

@@ -42,6 +42,7 @@ Stage0 vm now will show an error message if the size of the rom exceeds the avai
 ** Fixed
 Updated checksums to reflect changes in stage2 FORTH
 Fixed dis behavior in regards to hex values in strings
+Updated checksums to reflect changes in stage2 Lisp
 
 ** Removed
 the HERE and DP! are gone from ' now in stage3 FORTH

bootstrapping Steps.org

@@ -152,7 +152,7 @@ Then we use our M0 Line macro assembler to convert our assembly into hex2 format
 Then we need to assemble that hex into our desired program:
 ./bin/vm --rom roms/stage1_assembler-2 --tape_01 temp2 --tape_02 roms/lisp --memory 48K
 
-roms/lisp should have the sha256sum of 4c146297da8c672955698a82207295b28feb389c9856a2c6ea6a60ce7e84260a
+roms/lisp should have the sha256sum of b386b0e08250421a4d7eb14817b4c3359aef52d7773b3667bb1caaa933cbfe66
 
 Our lisp will first attempt to evaluate any code in tape_01 and then evaluate any code that the user types in.
 It is recommended to run with no less than 4MB of Memory

stage2/lisp.s

@@ -29,11 +29,21 @@
 
 ;; Start function
 :start
+	;; Check if we are going to hit outside the world
+	HAL_MEM                     ; Get total amount of Memory
+	LOADR R1 @MINIMAL_MEMORY    ; Get our Minimal Value
+	CMPSKIP.GE R0 R1            ; Check if we have enough
+	JUMP @FAILED_INITIALIZATION ; If not fail gracefully
+
 	LOADR R15 @stack_start      ; Put stack after CONS and HEAP
 	;; We will be using R14 for our condition codes
 	;; We will be using R13 for which Input we will be using
 	;; We will be using R12 for which Output we will be using
 
+	;; Ensure a known good state
+	FALSE R0                    ; Reset R0
+	FALSE R1                    ; Reset R1
+
 	;; Initialize
 	CALLI R15 @garbage_init
 	CALLI R15 @init_sl3
@@ -69,6 +79,22 @@
 :stack_start
 	'00180000'
 
+
+;; How much memory is too little
+:MINIMAL_MEMORY
+'00180000'
+
+;; Halt the machine in the event of insufficient Memory
+:FAILED_INITIALIZATION
+	FALSE R1                    ; Set output to TTY
+	LOADUI R0 $FAILED_STRING    ; Prepare our Message
+	CALLI R15 @Print_String     ; Print it
+	HALT                        ; Prevent any further damage
+
+:FAILED_STRING
+"Please provide 1600KB of Memory for this Lisp to run (More is recommended for large programs)
+"
+
 ;; Append_Cell
 ;; Adds a cell to the end of a CDR chain
 ;; Recieves HEAD in R0 and Tail in R1

test/SHA256SUMS

@@ -1,7 +1,7 @@
 8f465d3ec1cba00a7d024a1964e74bb6d241f86a73c77d95d8ceb10d09c8f7b9  roms/CAT
 59f0502748af32e3096e026a95e77216179cccfe803a05803317414643e2fcec  roms/DEHEX
 3a4a15691297345ac808ce41fae26d5592cd09d759d2feef88c1ef262ddaa5b8  roms/forth
-4c146297da8c672955698a82207295b28feb389c9856a2c6ea6a60ce7e84260a  roms/lisp
+b386b0e08250421a4d7eb14817b4c3359aef52d7773b3667bb1caaa933cbfe66  roms/lisp
 2b9727381aec15a504c0898189fbc2344209d8e04451e3fa5d743e08e38f64cf  roms/M0
 24a4d74eb2eb7a82e68335643855658b27b5a6c3b13db473539f3e08d6f26ceb  roms/SET
 0a427b14020354d1c785f5f900677e0059fce8f8d4456e9c19e5528cb17101eb  roms/stage0_monitor