git.sur5r.net Git - cc65/blob - libsrc/pce/crt0.s

   1 ;
   2 ; Startup code for cc65 (PCEngine version)
   3 ;
   4 ; by Groepaz/Hitmen <groepaz@gmx.net>
   5 ; based on code by Ullrich von Bassewitz <uz@cc65.org>
   6 ;
   7 ; This must be the *first* file on the linker command line
   8 ;
   9
  10         .export         _exit
  11         .export         __STARTUP__ : absolute = 1      ; Mark as startup
  12         .import         initlib, donelib
  13         .import     push0, _main, zerobss
  14         .import     initheap
  15         .import         tmp1,tmp2,tmp3
  16
  17         .import         __RAM_START__, __RAM_SIZE__     ; Linker generated
  18 ;;      .import         __SRAM_START__, __SRAM_SIZE__   ; Linker generated
  19         .import         __ROM0_START__, __ROM0_SIZE__   ; Linker generated
  20         .import         __ROM_START__, __ROM_SIZE__     ; Linker generated
  21         .import         __STARTUP_LOAD__,__STARTUP_RUN__, __STARTUP_SIZE__      ; Linker generated
  22         .import         __CODE_LOAD__,__CODE_RUN__, __CODE_SIZE__       ; Linker generated
  23         .import         __RODATA_LOAD__,__RODATA_RUN__, __RODATA_SIZE__ ; Linker generated
  24         .import         __DATA_LOAD__,__DATA_RUN__, __DATA_SIZE__       ; Linker generated
  25         .import __BSS_SIZE__
  26
  27         .include "pcengine.inc"
  28
  29     .importzp       sp
  30         .importzp       ptr1,ptr2
  31
  32 ; ------------------------------------------------------------------------
  33 ; Create an empty LOWCODE segment to avoid linker warnings
  34
  35 .segment        "LOWCODE"
  36
  37 ; ------------------------------------------------------------------------
  38 ; Place the startup code in a special segment.
  39
  40 .segment        "STARTUP"
  41
  42 start:
  43
  44 ; setup the CPU and System-IRQ
  45
  46                 ; Initialize CPU
  47
  48                 sei
  49                 nop
  50                 csh     ; set high speed CPU mode
  51                 nop
  52                 cld
  53                 nop
  54
  55                 ; Setup stack and memory mapping
  56                 ldx     #$FF    ; Stack top ($21FF)
  57                 txs
  58
  59                 ; at startup all MPRs are set to 0, so init them
  60                 lda     #$ff
  61                 tam     #1         ; 0000-1FFF = Hardware page
  62                 lda     #$F8
  63                 tam     #2         ; 2000-3FFF = Work RAM
  64                 ;lda     #$F7
  65                 ;tam     #2      ; 4000-5FFF = Save RAM
  66                 ;lda     #1
  67                 ;tam     #3      ; 6000-7FFF  Page 2
  68                 ;lda     #2
  69                 ;tam     #4      ; 8000-9FFF  Page 3
  70                 ;lda     #3
  71                 ;tam     #5      ; A000-BFFF  Page 4
  72                 ;lda     #4
  73                 ;tam     #6      ; C000-DFFF  Page 5
  74                 ;lda     #0
  75                 ;tam     #7      ; e000-fFFF  hucard/syscard bank 0
  76
  77                 ; Clear work RAM (2000-3FFF)
  78                 stz     <$00
  79                 tii     $2000, $2001, $1FFF
  80
  81                 ; Initialize hardware
  82                 stz     TIMER_COUNT   ; Timer off
  83                 lda     #$07
  84                 sta     IRQ_MASK     ; Interrupts off
  85                 stz     IRQ_STATUS   ; Acknowledge timer
  86
  87                 ;; i dont know why the heck this one doesnt
  88                 ;; work when called from a constructor :/
  89                         .import vdc_init
  90                         jsr     vdc_init
  91
  92 ;;                        jsr     joy_init
  93
  94                 ; Turn on background and VD interrupt/IRQ1
  95
  96                 lda     #$05
  97                 sta     IRQ_MASK           ; IRQ1=on
  98
  99                 cli
 100
 101 ; Clear the BSS data
 102
 103                 jsr     zerobss
 104
 105 ; Copy the .data segment to RAM
 106
 107                 lda #<(__DATA_LOAD__)
 108                 ;;lda #<(__ROM0_START__ + __STARTUP_SIZE__+ __CODE_SIZE__+ __RODATA_SIZE__)
 109                 ;;lda #<(__ROM_START__ + __CODE_SIZE__+ __RODATA_SIZE__)
 110                 sta ptr1
 111                 lda #>(__DATA_LOAD__)
 112                 ;;lda #>(__ROM_START__ + __CODE_SIZE__+ __RODATA_SIZE__)
 113                 sta ptr1+1
 114                 lda #<(__DATA_RUN__)
 115                 ;;lda #<(__SRAM_START__)
 116                 sta ptr2
 117                 lda #>(__DATA_RUN__)
 118                 ;;lda #>(__SRAM_START__)
 119                 sta ptr2+1
 120
 121                 ldx #>(__DATA_SIZE__)
 122
 123 @l2:
 124                 beq @s1 ; no more full pages
 125
 126                 ; copy one page
 127                 ldy #0
 128 @l1:
 129                 lda (ptr1),y
 130                 sta (ptr2),y
 131                 iny
 132                 bne @l1
 133
 134                 inc ptr1+1
 135                 inc ptr2+1
 136
 137                 dex
 138                 bne @l2
 139
 140                 ; copy remaining bytes
 141 @s1:
 142
 143                 ; copy one page
 144                 ldy #0
 145 @l3:
 146                 lda (ptr1),y
 147                 sta (ptr2),y
 148                 iny
 149                 cpy #<(__DATA_SIZE__)
 150                 bne @l3
 151
 152 ; setup the stack
 153
 154 ;               lda #<(__RAM_START__ + __DATA_SIZE__ + __BSS_SIZE__)
 155         lda #<(__RAM_START__+__RAM_SIZE__)
 156                 sta     sp
 157 ;               lda     #>(__RAM_START__ + __DATA_SIZE__ + __BSS_SIZE__)
 158         lda #>(__RAM_START__+__RAM_SIZE__)
 159         sta     sp+1            ; Set argument stack ptr
 160
 161 ; Init the Heap
 162                 jsr initheap
 163
 164 ;jmp *
 165
 166 ; Call module constructors
 167
 168                 jsr     initlib
 169
 170                 .import initconio
 171                 jsr initconio
 172
 173 ; Pass an empty command line
 174
 175
 176 ;jmp *
 177
 178                 jsr push0               ; argc
 179                 jsr     push0           ; argv
 180 go:
 181                 ldy     #4              ; Argument size
 182         jsr     _main   ; call the users code
 183
 184 ; Call module destructors. This is also the _exit entry.
 185
 186 _exit:
 187                 jsr     donelib         ; Run module destructors
 188
 189 ; reset the PCEngine
 190
 191                 jmp start
 192
 193 ; ------------------------------------------------------------------------
 194 ; System V-Blank Interupt
 195 ; ------------------------------------------------------------------------
 196
 197 _irq1:
 198                 pha
 199                 phx
 200                 phy
 201
 202
 203                 inc _tickcount
 204                 bne @s
 205                 inc _tickcount+1
 206 @s:
 207
 208                 ; Acknowlege interrupt
 209                 ldaio VDC_CTRL
 210
 211                 ply
 212                 plx
 213                 pla
 214                 rti
 215 _irq2:
 216                 rti
 217 _nmi:
 218                 rti
 219 _timer:
 220                 stz     IRQ_STATUS
 221                 rti
 222
 223                 .export initmainargs
 224 initmainargs:
 225                 rts
 226
 227 ; ------------------------------------------------------------------------
 228 ; hardware vectors
 229 ; ------------------------------------------------------------------------
 230     .segment "VECTORS"
 231     ;;.org    $fff6
 232
 233     .word   _irq2        ; $fff6 IRQ2 (External IRQ, BRK)
 234     .word   _irq1        ; $fff8 IRQ1 (VDC)
 235     .word   _timer       ; $fffa Timer
 236     .word   _nmi         ; $fffc NMI
 237     .word   start                ; $fffe reset
 238
 239
 240