FEAT: added libc-init support for Syllable and Darwin. Fixes long-sta…

…nding issue #129.

red-system/runtime/start.reds

@@ -23,9 +23,46 @@ system: declare struct! [							;-- trimmed down temporary system definition
 #switch OS [
 	Windows []										;-- nothing to do, initialization occurs in DLL init entry point
 	Syllable [
-
+		#import [LIBC-file cdecl [
+			libc-start: "__libc_start_main" [
+				main 			[function! []]
+				argv 			[pointer! [integer!]]
+				envp 			[pointer! [integer!]]
+				init 			[function! []]
+				finish 			[function! []]
+				stack-end 		[pointer! [integer!]]
+			]
+		]]
+
+		;; Clear the frame pointer. The SVR4 ELF/i386 ABI suggests this, to
+		;; mark the outermost frame.
+		system/stack/frame: as pointer! [integer!] 0
+
+		;; Extract arguments from the call stack (which was setup by the
+		;; kernel).
+		;; esp:   dummy value
+		;; esp+4: **argv
+		***__argv: system/stack/top + 1
+		***__argv: as [pointer! [integer!]] ***__argv/value
+		;; esp+8: **envp
+		***__envp: system/stack/top + 2
+		***__envp: as [pointer! [integer!]] ***__envp/value
+
+		;; Before pushing arguments for `libc-start`, align the stack to a
+		;; 128-bit boundary, to prevent misaligned access penalities.
+		system/stack/top: as pointer! [integer!] (FFFFFFF0h and as integer! ***__argv)
+
+		;; The call to `libc-start` takes 6 4-byte arguments (passed on the
+		;; stack). To keep the stack 128-bit aligned even after the call, we
+		;; push some garbage.
+		push 0
+		push 0
+
+		;; Finally, call into libc's startup routine.
+		***__stack_end: system/stack/top
+		libc-start :***_start ***__argv ***__envp null null ***__stack_end		
 	]
-	#default [
+	#default [										;-- for SVR4 fully conforming UNIX platforms
 		#import [LIBC-file cdecl [
 			libc-start: "__libc_start_main" [
 				main 			[function! []]

red-system/runtime/syllable.reds

@@ -34,11 +34,20 @@ Red/System [
 ;-------------------------------------------
 ;-- Retrieve command-line information from stack
 ;-------------------------------------------
-pop											;-- dummy value
-system/args-list: as str-array! pop			;-- &argv
-system/env-vars: as str-array! pop			;-- &envp
 
-***-on-start: func [/local c argv][
+#either use-natives? = yes [
+	pop										;-- dummy value
+	system/args-list: as str-array! pop		;-- &argv
+	system/env-vars:  as str-array! pop		;-- &envp
+
+][
+	;-- the current stack is pointing to main(int argc, void **argv, void **envp) C layout
+	;-- we avoid the double indirection by reusing our variables from %start.reds
+	system/args-list: as str-array! ***__argv
+	system/env-vars:  as str-array! ***__envp
+]
+
+***-get-argc: func [/local c argv][
 	argv: system/args-list
 	c: 0
 	while [argv/item <> null][
@@ -47,6 +56,6 @@ system/env-vars: as str-array! pop			;-- &envp
 	]
 	system/args-count: c
 ]
-***-on-start
-
+***-get-argc
+	
 #include %POSIX.reds