Update crt0.s

[cc65] / libsrc / pce / crt0.s

diff --git a/libsrc/pce/crt0.s b/libsrc/pce/crt0.s
index 80b32c0892f5e84d1cb38acec8052bba530a5cf5..16e69fc4dc1110ae975afde905679563fd1b56ee 100644 (file)
--- a/libsrc/pce/crt0.s
+++ b/libsrc/pce/crt0.s
@@ -4,33 +4,26 @@
 ; by Groepaz/Hitmen <groepaz@gmx.net>
 ; based on code by Ullrich von Bassewitz <uz@cc65.org>
 ;
-; This must be the *first* file on the linker command line
+; 2018-02-11, Greg King
 ;
 
         .export         _exit
         .export         __STARTUP__ : absolute = 1      ; Mark as startup
 
         .import         initlib, donelib
-        .import         push0, _main, zerobss
-        .import         initheap
+        .import         push0, _main
         .import         IRQStub
 
-        ; Linker generated
-        .import         __RAM_START__, __RAM_SIZE__
-        .import         __ROM0_START__, __ROM0_SIZE__
-        .import         __ROM_START__, __ROM_SIZE__
-        .import         __STARTUP_LOAD__,__STARTUP_RUN__, __STARTUP_SIZE__
-        .import         __CODE_LOAD__,__CODE_RUN__, __CODE_SIZE__
-        .import         __RODATA_LOAD__,__RODATA_RUN__, __RODATA_SIZE__
-        .import         __DATA_LOAD__,__DATA_RUN__, __DATA_SIZE__
-        .import         __BSS_SIZE__
+        ; Linker-generated
+        .import         __CARTSIZE__
+        .import         __DATA_LOAD__, __DATA_RUN__, __DATA_SIZE__
+        .import         __BSS_RUN__, __BSS_SIZE__
+        .import         __MAIN_START__, __MAIN_SIZE__, __STACKSIZE__
 
         .include        "pce.inc"
         .include        "extzp.inc"
 
         .importzp       sp
-        .importzp       ptr1,ptr2
-        .importzp       tmp1,tmp2,tmp3
 
 ; ------------------------------------------------------------------------
 ; Place the startup code in a special segment.
@@ -46,36 +39,32 @@ start:
         nop
         csh                     ; Set high speed CPU mode
         nop
-        cld
-        nop
 
         ; Set up stack and memory mapping
         ldx     #$FF            ; Stack top ($21FF)
         txs
 
-        ; At startup all MPRs are set to 0, so init them
-        lda     #$ff
-        tam     #%00000001      ; 0000-1FFF = Hardware page
+        ; At power-on, most MPRs have random values; so, initiate them.
+        lda     #$FF
+        tam     #%00000001      ; $0000-$1FFF = Hardware bank
         lda     #$F8
-        tam     #%00000010      ; 2000-3FFF = Work RAM
-
-        ; FIXME: setup a larger block of memory to use with C-code
+        tam     #%00000010      ; $2000-$3FFF = Work RAM
         ;lda     #$F7
-        ;tam     #%00000100      ; 4000-5FFF = Save RAM
-        ;lda     #1
-        ;tam     #%00001000      ; 6000-7FFF  Page 2
-        ;lda     #2
-        ;tam     #%00010000      ; 8000-9FFF  Page 3
-        ;lda     #3
-        ;tam     #%00100000      ; A000-BFFF  Page 4
+        ;tam     #%00000100      ; $4000-$47FF = 2K Battery-backed RAM
         ;lda     #4
-        ;tam     #%01000000      ; C000-DFFF  Page 5
-        ;lda     #0
-        ;tam     #%10000000      ; e000-fFFF  hucard/syscard bank 0
-
-        ; Clear work RAM (2000-3FFF)
-        stz     <$00
-        tii     $2000, $2001, $1FFF
+        ;tam     #%00001000      ; $6000-$7FFF
+
+        lda     #$01
+        ldx     #>$8000
+        cpx     #>__CARTSIZE__
+        bcc     @L1             ;(blt)
+        tam     #%00010000      ; $8000-$9FFF = ROM bank 1 (32K block of ROM)
+        inc     a
+        tam     #%00100000      ; $A000-$BFFF = ROM bank 2
+        inc     a
+@L1:    tam     #%01000000      ; $C000-$DFFF = ROM bank 3 (32K) or 1 (16K)
+        ;lda    #$00            ; (The reset default)
+        ;tam    #%10000000      ; $E000-$FFFF  hucard/syscard bank 0
 
         ; Initialize hardware
         stz     TIMER_CTRL      ; Timer off
@@ -91,15 +80,16 @@ start:
         lda     #$05
         sta     IRQ_MASK        ; IRQ1=on
 
-        ; Clear the BSS data
-        jsr     zerobss
-
         ; Copy the .data segment to RAM
         tii     __DATA_LOAD__, __DATA_RUN__, __DATA_SIZE__
 
+        ; Clear the .bss segment
+        stz     __BSS_RUN__
+        tii     __BSS_RUN__, __BSS_RUN__ + 1, __BSS_SIZE__ - 1
+
         ; Set up the stack
-        lda     #<(__RAM_START__+__RAM_SIZE__)
-        ldx     #>(__RAM_START__+__RAM_SIZE__)
+        lda     #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+        ldx     #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
         sta     sp
         stx     sp + 1