From: Alan Cox <alan@linux.intel.com>
Date: Thu, 21 May 2015 22:09:07 +0000 (+0100)
Subject: Makefile: add a "nostdio" crt0
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=77583581381987b14a4db205cbd0ff68d7e146aa;p=FUZIX.git

Makefile: add a "nostdio" crt0
---

diff --git a/Library/libs/Makefile b/Library/libs/Makefile
index deb83767..ce3f4680 100644
--- a/Library/libs/Makefile
+++ b/Library/libs/Makefile
@@ -14,6 +14,8 @@ ASM_OPT = -l -o -s
 LINKER_OPT = -m -i -o
 SRC_CRT0 = crt0$(PLATFORM).s
 OBJ_CRT0 = $(SRC_CRT0:.s=.rel)
+SRC_CRT0NS = crt0nostdio$(PLATFORM).s
+OBJ_CRT0NS = $(SRC_CRT0NS:.s=.rel)
 SRC_ASM = enter.s
 OBJ_ASM = $(SRC_ASM:.s=.rel)
 SRC_C =  __argv.c abort.c asctime.c assert.c atexit.c
@@ -64,7 +66,7 @@ OBJ_C = $(SRC_C:.c=.rel)
 OBJ_HARD = $(SRC_HARD:.c=.rel)
 OBJ_ALL = $(OBJ_ASM) $(OBJ_C) $(OBJ_HARD)
 
-all: syslib$(PLATFORM).lib crt0$(PLATFORM).rel
+all: syslib$(PLATFORM).lib crt0$(PLATFORM).rel crt0nostdio$(PLATFORM).rel
 
 libc.l:%.l:$(OBJ_ALL)
 	ls $(OBJ_ALL) > libc.l
@@ -94,6 +96,9 @@ $(OBJ_ASM):%.rel: %.s
 $(OBJ_CRT0):%.rel: %.s
 	$(ASM) $(ASM_OPT) $@ $(@:.rel=.s)
 
+$(OBJ_CRT0NS):%.rel: %.s
+	$(ASM) $(ASM_OPT) $@ $(@:.rel=.s)
+
 $(OBJ_C):%.rel: %.c
 	$(CC) $(CC_OPT) $(@:.rel=.c)
 
diff --git a/Library/libs/crt0nostdio.s b/Library/libs/crt0nostdio.s
new file mode 100644
index 00000000..1ed5c7d5
--- /dev/null
+++ b/Library/libs/crt0nostdio.s
@@ -0,0 +1,80 @@
+		.module crt0
+
+		.area _CODE
+		.area _HOME
+		.area _CONST
+		; The _GS can be blown away after startup. We don't yet
+		; but we should do FIXME
+		.area _GSINIT
+		.area _GSFINAL
+		.area _INITIALIZED
+		.area _BSEG
+		.area _DATA
+		.area _BSS
+		; note that the binary builder moves the initialized data
+		; from initializer
+		.area _INITIALIZER
+
+		.globl _main
+		.globl _exit
+		.globl _environ
+		.globl ___argv
+
+		.globl s__DATA
+		.globl l__DATA
+		.globl s__INITIALIZED
+
+		.area _CODE
+
+; start at 0x100
+start:		jp start2
+		.db 'F'
+		.db 'Z'
+		.db 'X'
+		.db '1'
+
+;
+;	Borrowed idea from UMZIX - put the info in known places then
+;	we can write "size" tools
+;
+;	This is confusing. SDCC doesn't produce a BSS, instead it
+;	produces an INITIALIZED (which everyone else calls DATA) and a
+;	DATA which everyone else would think of as BSS.
+;
+;	FIXME: we need to automate the load page setting
+;
+		.db 0x01		; page to load at
+		.dw 0			; chmem ("0 - 'all'")
+		.dw s__INITIALIZED	; gives us code size info
+		.dw s__DATA		; gives us data size info
+		.dw l__DATA		; bss size info
+		.dw 0			; spare
+
+start2:		ld hl, #l__DATA - 1	 ; work around linker limit
+		ld b, h
+		ld c, l
+		ld hl, #s__DATA
+		ld de, #s__DATA+1
+		ld (hl), #0
+		ldir
+		call gsinit
+
+		ld hl, #4
+		add hl, sp
+		ld (_environ), hl
+		pop de			; argc
+		pop hl			; argv
+		push hl
+		ld (___argv), hl	; needed for stuff like err()
+		push de
+		ld hl, #_exit		; return vector
+		push hl
+		jp _main		; go
+
+		.area _GSINIT
+gsinit:
+		.area _GSFINAL
+		ret
+
+		.area _DATA
+_environ:	.dw 0