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
  51                         nop
  52                         cld
  53                         nop
  54
  55                         ; Setup stack and memory mapping
  56                         ldx     #$FF    ; Stack top ($21FF)
  57                         txs
  58                         txa
  59                         tam     #0      ; 0000-1FFF = Hardware page
  60
  61                         lda     #$F8
  62                         tam     #1      ; 2000-3FFF = Work RAM
  63
  64                         lda     #$F7
  65                         tam     #2      ; 4000-5FFF = Save RAM
  66
  67                                                 lda     #1
  68                         tam     #3      ; 6000-7FFF  Page 2
  69                                                 lda     #2
  70                         tam     #4      ; 8000-9FFF  Page 3
  71                                                 lda     #3
  72                         tam     #5      ; A000-BFFF  Page 4
  73                                                 lda     #4
  74                         tam     #6      ; C000-DFFF  Page 5
  75
  76                         ; Initialize hardware
  77                         stz     TIMER_COUNT   ; Timer off
  78                         lda     #$07
  79                         sta     IRQ_MASK     ; Interrupts off
  80                         stz     IRQ_STATUS   ; Acknowledge timer
  81
  82                         ; Clear work RAM
  83                         stz     <$00
  84                         tii     $2000, $2001, $1FFF
  85
  86                                                 ;; i dont know why the heck this one doesnt
  87                                                 ;; work when called from a constructor :/
  88                                                 .import vdc_init
  89                                                 jsr     vdc_init
  90 ;;                        jsr     joy_init
  91
  92                         ; Turn on background and VD interrupt/IRQ1
  93                         lda     #$05
  94                         sta     IRQ_MASK           ; IRQ1=on
  95                         cli
  96
  97 ; Clear the BSS data
  98
  99                 jsr     zerobss
 100
 101 ; Copy the .data segment to RAM
 102
 103                 lda #<(__DATA_LOAD__)
 104                 ;;lda #<(__ROM0_START__ + __STARTUP_SIZE__+ __CODE_SIZE__+ __RODATA_SIZE__)
 105                 ;;lda #<(__ROM_START__ + __CODE_SIZE__+ __RODATA_SIZE__)
 106                 sta ptr1
 107                 lda #>(__DATA_LOAD__)
 108                 ;;lda #>(__ROM_START__ + __CODE_SIZE__+ __RODATA_SIZE__)
 109                 sta ptr1+1
 110                 lda #<(__DATA_RUN__)
 111                 ;;lda #<(__SRAM_START__)
 112                 sta ptr2
 113                 lda #>(__DATA_RUN__)
 114                 ;;lda #>(__SRAM_START__)
 115                 sta ptr2+1
 116
 117                 ldx #>(__DATA_SIZE__)
 118
 119 @l2:
 120                 beq @s1 ; no more full pages
 121
 122                 ; copy one page
 123                 ldy #0
 124 @l1:
 125                 lda (ptr1),y
 126                 sta (ptr2),y
 127                 iny
 128                 bne @l1
 129
 130                 inc ptr1+1
 131                 inc ptr2+1
 132
 133                 dex
 134                 bne @l2
 135
 136                 ; copy remaining bytes
 137 @s1:
 138
 139                 ; copy one page
 140                 ldy #0
 141 @l3:
 142                 lda (ptr1),y
 143                 sta (ptr2),y
 144                 iny
 145                 cpy #<(__DATA_SIZE__)
 146                 bne @l3
 147
 148 ; setup the stack
 149
 150 ;               lda #<(__RAM_START__ + __DATA_SIZE__ + __BSS_SIZE__)
 151         lda #<(__RAM_START__+__RAM_SIZE__)
 152                 sta     sp
 153 ;               lda     #>(__RAM_START__ + __DATA_SIZE__ + __BSS_SIZE__)
 154         lda #>(__RAM_START__+__RAM_SIZE__)
 155         sta     sp+1            ; Set argument stack ptr
 156
 157 ; Init the Heap
 158                 jsr initheap
 159
 160 ;jmp *
 161
 162 ; Call module constructors
 163
 164                 jsr     initlib
 165 ;               .import initconio
 166 ;               jsr initconio
 167 ; Pass an empty command line
 168
 169
 170 ;jmp *
 171
 172                 jsr push0               ; argc
 173                 jsr     push0           ; argv
 174 go:
 175                 ldy     #4              ; Argument size
 176         jsr     _main   ; call the users code
 177
 178 ; Call module destructors. This is also the _exit entry.
 179
 180 _exit:
 181                 jsr     donelib         ; Run module destructors
 182
 183 ; reset the PCEngine
 184
 185                 jmp start
 186
 187 ; ------------------------------------------------------------------------
 188 ; System V-Blank Interupt
 189 ; ------------------------------------------------------------------------
 190
 191 _irq1:
 192                         pha
 193                         phx
 194                         phy
 195
 196
 197                 inc _tickcount
 198                 bne @s
 199                 inc _tickcount+1
 200 @s:
 201
 202                         ; Acknowlege interrupt
 203                                                 ldaio VDC_CTRL
 204
 205                                                 ply
 206                         plx
 207                         pla
 208                         rti
 209 _irq2:
 210                         rti
 211 _nmi:
 212                         rti
 213 _timer:
 214                         stz     IRQ_STATUS
 215                         rti
 216
 217         .export initmainargs
 218 initmainargs:
 219         rts
 220
 221 ; ------------------------------------------------------------------------
 222 ; hardware vectors
 223 ; ------------------------------------------------------------------------
 224     .segment "VECTORS"
 225     ;;.org    $fff6
 226
 227     .word   _irq2        ; $fff6 IRQ2 (External IRQ, BRK)
 228     .word   _irq1        ; $fff8 IRQ1 (VDC)
 229     .word   _timer       ; $fffa Timer
 230     .word   _nmi         ; $fffc NMI
 231     .word   start                ; $fffe reset
 232
 233
 234