Makefile: add a "nostdio" crt0

diff --git a/Library/libs/Makefile b/Library/libs/Makefile
index deb8376..ce3f468 100644 (file)
--- 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 (file)
index 0000000..1ed5c7d
--- /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