hexed/hexed.s

   1 ##################################################
   2 #                                                #
   3 # Assemble with gas                              #
   4 #   --register-prefix-optional --bitwise-or      #
   5 #                                                #
   6 ##################################################
   7
   8 .text
   9 .globl main
  10 .globl VBL
  11
  12 ##################################################
  13 #                                                #
  14 #        Register and bitmask definitions        #
  15 #                                                #
  16 ##################################################
  17
  18 .equ GFXDATA,           0xc00000
  19 .equ GFXCNTL,           0xc00004
  20
  21 .equ VDP0_E_HBI,        0x10
  22 .equ VDP0_E_DISPLAY,    0x02
  23 .equ VDP0_PLTT_FULL,    0x04
  24
  25 .equ VDP1_SMS_MODE,     0x80
  26 .equ VDP1_E_DISPLAY,    0x40
  27 .equ VDP1_E_VBI,        0x20
  28 .equ VDP1_E_DMA,        0x10
  29 .equ VDP1_NTSC,         0x00
  30 .equ VDP1_PAL,          0x08
  31 .equ VDP1_RESERVED,     0x04
  32
  33 .equ VDP12_SPR_SHADOWS, 0x08
  34 .equ VDP12_SCREEN_V224, 0x00
  35 .equ VDP12_SCREEN_V448, 0x04
  36 .equ VDP12_PROGRESSIVE, 0x00
  37 .equ VDP12_INTERLACED,  0x02
  38 .equ VDP12_SCREEN_H256, 0x00
  39 .equ VDP12_SCREEN_H320, 0x81
  40
  41 .equ VDP16_MAP_V32,     0x00
  42 .equ VDP16_MAP_V64,     0x10
  43 .equ VDP16_MAP_V128,    0x30
  44 .equ VDP16_MAP_H32,     0x00
  45 .equ VDP16_MAP_H64,     0x01
  46 .equ VDP16_MAP_H128,    0x03
  47
  48
  49
  50 ##################################################
  51 #                                                #
  52 #                   MACROS                       #
  53 #                                                #
  54 ##################################################
  55
  56
  57 /* Write val to VDP register reg */
  58 .macro write_vdp_reg reg val
  59         move.w #((\reg << 8) + 0x8000 + \val),(a3)
  60 .endm
  61
  62
  63 /* For immediate addresses */
  64 .macro VRAM_ADDR reg adr
  65         move.l #(((0x4000 + (\adr & 0x3fff)) << 16) + (\adr >> 14)),\reg
  66 .endm
  67
  68
  69 .macro CRAM_ADDR reg adr
  70         move.l  #(((0xc000 + (\adr & 0x3fff)) << 16) + (\adr >> 14)),\reg
  71 .endm
  72
  73
  74 # make VDP word from address adr and store in d0
  75 .macro XRAM_ADDR_var adr
  76         move.l \adr,d0
  77         lsl.l #8,d0
  78         lsl.l #8,d0
  79         rol.l #2,d0
  80         lsl.b #2,d0
  81         lsr.l #2,d0
  82 .endm
  83
  84
  85 .macro VRAM_ADDR_var adr
  86         XRAM_ADDR_var \adr
  87         or.l #0x40000000,d0
  88 .endm
  89
  90
  91 .macro CRAM_ADDR_var adr
  92         XRAM_ADDR_var \adr
  93         or.l #0xc0000000,d0
  94 .endm
  95
  96
  97 .macro VSCROLL_ADDR reg adr
  98         move.l  #(((0x4000 + (\adr & 0x3fff)) << 16) + ((\adr >> 14) | 0x10)),\reg
  99 .endm
 100
 101
 102 .macro HSCROLL_ADDR reg adr
 103         move.l #(((0x4000 + (\adr & 0x3fff)) << 16) + (\adr >> 14)),\reg
 104 .endm
 105
 106
 107 # convert tile coords in d0, d1 to nametable addr to a0
 108 .macro XY2NT
 109         lsl.w           #6,d1
 110         add.w           d1,d0
 111         lsl.w           #1,d0
 112         movea.l         #0xe000,a0
 113         add.w           d0,a0
 114 .endm
 115
 116 # check if some d-pad button (and modifier) is pressed
 117 .macro do_dpad bit op opq val modval
 118         btst.b          #\bit,d0
 119         beq             1f
 120         btst.b          #4,d0           /* A pressed? */
 121         bne             0f
 122         \opq.l          #\val,a6
 123         bra             input_end
 124 0:
 125         \op.l           #\modval,a6
 126         bra             input_end
 127 1:
 128 .endm
 129
 130 #################################################
 131 #                                               #
 132 #                    DATA                       #
 133 #                                               #
 134 #################################################
 135
 136 colors:
 137         dc.w 0x0000,0x0eee,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 138         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 139         dc.w 0x0000,0x02e2,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 140         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 141         dc.w 0x0000,0x0e44,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 142         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 143 colors_end:
 144
 145
 146 sprite_data:
 147         /*         Y        size     link          attr        X */
 148         dc.w       0;  dc.b 0x05;  dc.b 0;  dc.w 0x6002;  dc.w 0
 149 sprite_data_end:
 150
 151 ##################################################
 152 #                                                #
 153 #               MAIN PROGRAM                     #
 154 #                                                #
 155 ##################################################
 156
 157 .align 2
 158
 159 main:
 160         /* mask irqs during init */
 161         move.w          #0x2700,sr
 162
 163         movea.l         #0,a6
 164         moveq.l         #0,d7
 165
 166         /* Init pads */
 167         move.b          #0x40,(0xa10009).l
 168         move.b          #0x40,(0xa10003).l
 169
 170         /* Initialize VDP */
 171         jsr             init_gfx
 172
 173         /* Load color data */
 174         movea.l         #0,a0
 175         movea.l         #colors,a1
 176         moveq.l         #(colors_end-colors)/2,d0
 177         jsr             load_colors
 178
 179         /* load patterns */
 180         movea.l         #0,a0
 181         movea.l         #font,a1
 182         move.l          #128,d0
 183         jsr             load_tiles
 184
 185         /* generate A layer map */
 186         movea.l         #0xe000,a1
 187         move.l          #28-1,d4
 188 lmaploop0:
 189         movea.l         a1,a0
 190         jsr             load_prepare
 191
 192         move.l          #64/2-1,d3
 193 0:      move.l          #0x00000000,(a0)
 194         dbra            d3,0b
 195
 196         add.l           #64*2,a1
 197         dbra            d4,lmaploop0
 198
 199         /* generate B layer map */
 200         movea.l         #0xc000,a0
 201         jsr             load_prepare
 202
 203         move.l          #64*28/2-1,d3
 204 0:      move.l          #0x00000000,(a0)
 205         dbra            d3,0b
 206
 207         /* upload sprite data */
 208         movea.l         #0xfc00,a0
 209         jsr             load_prepare
 210         movea.l         #sprite_data,a1
 211
 212         move.l          #(sprite_data_end-sprite_data)/2-1,d3
 213 0:      move.l          (a1)+,(a0)
 214         dbra            d3,0b
 215
 216         move.w          #0x2000,sr
 217
 218 ##################################################
 219 #                                                #
 220 #                 MAIN LOOP                      #
 221 #                                                #
 222 ##################################################
 223
 224 # global regs:
 225 # a6 - page_start[31:8]|cursor_offs[7:0]
 226 # d7 - byte_mode[0]
 227
 228 forever:
 229
 230
 231         jsr             wait_vsync
 232         bra             forever
 233
 234
 235
 236 VBL:
 237         addq.l          #1,(vtimer).l
 238         movem.l         d0-d6/a0-a5,-(a7)
 239
 240         /* draw main stuff */
 241         clr.l           d1
 242         move.l          a6,d0
 243         move.b          d0,d1
 244         lsr.l           #8,d0
 245         move.l          d0,a1           /* current addr */
 246         lsr.b           #3,d1
 247         neg.b           d1
 248         add.b           #27-1,d1        /* line where the cursor sits */
 249         swap            d1
 250
 251         movea.l         #0xe004,a2
 252         move.l          #27-1,d5        /* line counter for dbra */
 253         or.l            d1,d5
 254
 255 draw_column:
 256         move.l          a2,a0
 257         jsr             load_prepare
 258
 259         /* addr */
 260         move.l          a1,d2
 261         moveq.l         #6,d3
 262         jsr             print_hex_preped
 263
 264         /* 4 shorts */
 265         moveq.l         #4,d3
 266         moveq.l         #4-1,d4
 267 draw_shorts:
 268         move.w          #' ',(a0)
 269         move.w          (a1)+,d2
 270         jsr             print_hex_preped
 271         dbra            d4,draw_shorts
 272
 273         move.l          d5,d0
 274         swap            d0
 275         cmp.w           d5,d0
 276         beq             draw_cursor
 277
 278 draw_chars_pre:
 279         move.l          #(' '<<16)|' ',(a0)
 280
 281         /* 8 chars */
 282         subq.l          #8,a1
 283         moveq.l         #8-1,d4
 284 draw_chars:
 285         move.b          (a1)+,d0
 286         move.b          d0,d1
 287         sub.b           #0x20,d1
 288         cmp.b           #0x60,d1
 289         blo             0f
 290         move.w          #'.',d0
 291 0:
 292         move.w          d0,(a0)
 293         dbra            d4,draw_chars
 294
 295         add.w           #0x80,a2
 296         dbra            d5,draw_column
 297
 298         /* status bar */
 299         movea.l         #0xe004+64*2*27,a0
 300         jsr             load_prepare
 301         move.l          a6,d2
 302         moveq.l         #0,d3
 303         move.b          d2,d3
 304         lsr.l           #8,d2
 305         add.l           d3,d2
 306         move.l          #0x4006,d3
 307         jsr             print_hex_preped
 308
 309         /* handle input */
 310         jsr             get_input               /* x0cbrldu x1sa00du */
 311
 312         do_dpad         0,  sub, subq, 0x0008, 0x0800
 313         do_dpad         1,  add, addq, 0x0008, 0x0800
 314         do_dpad         10, sub, subq, 0x0001, 0xd800
 315         do_dpad         11, add, addq, 0x0001, 0xd800
 316 input_end:
 317
 318         /* update addr */
 319         move.l          a6,d0
 320         cmp.b           #0xf0,d0
 321         blo             0f
 322         sub.l           #0xd800,a6
 323         add.w           #0x00d8,a6
 324         bra             1f
 325 0:
 326         cmp.b           #0xe0,d0
 327         blo             1f
 328         add.l           #0xd800,a6
 329         sub.w           #0x00d8,a6
 330 1:
 331
 332 end:
 333         movem.l         (a7)+,d0-d6/a0-a5
 334         rte
 335
 336
 337 draw_cursor:
 338         move.l          a6,d0
 339         and.l           #7,d0           /* byte offs */
 340         move.l          d0,d1
 341         lsr.b           #1,d1           /* which word */
 342         move.b          d1,d2
 343         lsl.b           #2,d2
 344         add.b           d2,d1           /* num of chars to skip */
 345         lsl.b           #1,d1
 346
 347         /* FIXME */
 348         move.w          (-8,a1,d0),d2
 349
 350         lea             (7*2,a2,d1),a0
 351         jsr             load_prepare
 352
 353         move.w          #0x2004,d3
 354         jsr             print_hex_preped
 355
 356         move.l          a2,a0
 357         add.w           #26*2,a0
 358         jsr             load_prepare    /* restore a0 */
 359
 360         jmp             draw_chars_pre
 361
 362
 363 #################################################
 364 #                                               #
 365 #         Initialize VDP registers              #
 366 #                                               #
 367 #################################################
 368
 369 init_gfx:
 370         move.l          #GFXCNTL,a3
 371         write_vdp_reg   0,(VDP0_E_DISPLAY | VDP0_PLTT_FULL)
 372         write_vdp_reg   1,(VDP1_E_VBI | VDP1_E_DISPLAY | VDP1_E_DMA | VDP1_RESERVED)
 373         write_vdp_reg   2,(0xe000 >> 10)        /* Screen map a adress */
 374         write_vdp_reg   3,(0xe000 >> 10)        /* Window address */
 375         write_vdp_reg   4,(0xc000 >> 13)        /* Screen map b address */
 376         write_vdp_reg   5,(0xfc00 >>  9)        /* Sprite address */
 377         write_vdp_reg   6,0
 378         write_vdp_reg   7,0                     /* Backdrop color */
 379         write_vdp_reg   10,1                    /* Lines per hblank interrupt */
 380         write_vdp_reg   11,0                    /* 2-cell vertical scrolling */
 381         write_vdp_reg   12,(VDP12_SCREEN_V224 | VDP12_SCREEN_H320)
 382         write_vdp_reg   13,(0x8000 >> 10)       /* Horizontal scroll address */
 383         write_vdp_reg   15,2
 384         write_vdp_reg   16,(VDP16_MAP_V32 | VDP16_MAP_H64)      /* layer size */
 385         write_vdp_reg   17,0
 386         write_vdp_reg   18,0xff
 387         rts
 388
 389
 390 # read single phase from controller
 391 #  a0 - addr
 392 #  d0 - result
 393 get_input:
 394         move.b          #0x40,(0xa10003)
 395         nop
 396         nop
 397         nop
 398         move.b          (0xa10003),d0
 399         move.b          #0x00,(0xa10003)
 400         lsl.w           #8,d0
 401         nop
 402         move.b          (0xa10003),d0
 403         eor.w           #0xffff,d0
 404 #       move.b          #0x40,(0xa10003)
 405         rts
 406
 407 # Load tile data from ROM
 408 #  a0: VRAM base
 409 #  a1: pattern address
 410 #  d0: number of tiles to load
 411 #  destroys d1
 412
 413 load_tiles:
 414         move.l          d0,d1
 415         VRAM_ADDR_var   a0
 416         move.l          d0,(GFXCNTL).l
 417
 418         move.l          #GFXDATA,a0
 419         lsl.w           #3,d1
 420         subq.l          #1,d1
 421 0:
 422         move.l          (a1)+,(a0)
 423         dbra            d1,0b
 424
 425         rts
 426
 427
 428 # Prepare to write to VDP RAM @a3
 429 # sets a0 to VDP data port for convenience
 430 #  a0: VRAM base
 431 #  destroys d0
 432
 433 load_prepare:
 434         VRAM_ADDR_var   a0
 435         move.l          d0,(GFXCNTL).l
 436         move.l          #GFXDATA,a0
 437         rts
 438
 439
 440 # Load color data from ROM
 441 #  a0: CRAM base
 442 #  a1: color list address
 443 #  d0: number of colors to load
 444 #  destroys d1
 445
 446 load_colors:
 447         move.l          d0,d1
 448         CRAM_ADDR_var   a0
 449         move.l          d0,(GFXCNTL).l
 450
 451         move.l          #GFXDATA,a0
 452         subq.w          #1,d1
 453 0:
 454         move.w          (a1)+,(a0)
 455         dbra            d1,0b
 456
 457         rts
 458
 459
 460 # print
 461 #  a0 - string
 462 #  d0 - x
 463 #  d1 - y
 464 #  destroys a1
 465
 466 print:
 467         move.l          a0,a1
 468         XY2NT
 469         jsr             load_prepare
 470         moveq.l         #0,d0
 471
 472 _print_loop:
 473         move.b          (a1)+,d0
 474         beq             _print_end
 475
 476         move.w          d0,(a0)
 477         jmp             _print_loop
 478
 479 _print_end:
 480         rts
 481
 482
 483 # print_hex
 484 #  d0 - x
 485 #  d1 - y
 486 #  d2 - value
 487 #  d3 - digit_cnt[0:7]|tile_bits[11:15]
 488 #  destroys a0, preserves d3
 489
 490 print_hex:
 491         XY2NT
 492         jsr             load_prepare
 493
 494 print_hex_preped:
 495         moveq.l         #0,d0
 496         move.b          d3,d0
 497         move.l          d0,d1
 498         lsl.b           #2,d0
 499         ror.l           d0,d2           /* prep value */
 500         subq.l          #1,d1           /* count */
 501         move.w          d3,d0
 502         and.w           #0xf800,d0      /* keep upper bits in d0 */
 503
 504 _print_hex_loop:
 505         rol.l           #4,d2
 506         move.b          d2,d0
 507         and.b           #0xf,d0
 508
 509         add.b           #'0',d0
 510         cmp.b           #'9',d0
 511         ble             0f
 512         addq.b          #7,d0
 513 0:
 514         move.w          d0,(a0)
 515         dbra            d1,_print_hex_loop
 516
 517         rts
 518
 519
 520 #################################################
 521 #                                               #
 522 #       Wait for next VBlank interrupt          #
 523 #                                               #
 524 #################################################
 525
 526 wait_vsync:
 527         movea.l         #vtimer,a0
 528         move.l          (a0),a1
 529 _wait_change:
 530         stop            #0x2000
 531         cmp.l           (a0),a1
 532         beq             _wait_change
 533         rts
 534
 535
 536 #################################################
 537 #                                               #
 538 #                 RAM DATA                      #
 539 #                                               #
 540 #################################################
 541
 542 .bss
 543
 544 # used by sega_gcc.s
 545 .globl htimer
 546 .globl vtimer
 547 .globl rand_num
 548 htimer:         .long 0
 549 vtimer:         .long 0
 550 rand_num:       .long 0
 551
 552 #
 553
 554 .end
 555
 556 # vim:filetype=asmM68k