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_STE,         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 val
 118         btst.l          #\bit,d0
 119         beq             0f
 120         \op.l           \val,a6
 121         bra             dpad_end
 122 0:
 123 .endm
 124
 125 #################################################
 126 #                                               #
 127 #                    DATA                       #
 128 #                                               #
 129 #################################################
 130
 131 colors:
 132         dc.w 0x0000,0x0eee,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 133         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 134         dc.w 0x0000,0x02e2,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 135         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 136         dc.w 0x0000,0x0e44,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 137         dc.w    0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
 138 colors_end:
 139
 140
 141 sprite_data:
 142         /*         Y        size     link          attr        X */
 143         dc.w       0;  dc.b 0x05;  dc.b 0;  dc.w 0x6002;  dc.w 0
 144 sprite_data_end:
 145
 146 ##################################################
 147 #                                                #
 148 #               MAIN PROGRAM                     #
 149 #                                                #
 150 ##################################################
 151
 152 .align 2
 153
 154 main:
 155         /* mask irqs during init */
 156         move.w          #0x2700,sr
 157
 158         movea.l         #0,a6
 159         moveq.l         #0,d7
 160         moveq.l         #0,d6
 161
 162         /* Init pads */
 163         move.b          #0x40,(0xa10009).l
 164         move.b          #0x40,(0xa10003).l
 165
 166         /* Initialize VDP */
 167         jsr             init_gfx
 168
 169         /* Load color data */
 170         movea.l         #0,a0
 171         movea.l         #colors,a1
 172         moveq.l         #(colors_end-colors)/2,d0
 173         jsr             load_colors
 174
 175         /* load patterns */
 176         movea.l         #0,a0
 177         movea.l         #font,a1
 178         move.l          #128,d0
 179         jsr             load_tiles
 180
 181         /* generate A layer map */
 182         movea.l         #0xe000,a1
 183         move.l          #28-1,d4
 184 lmaploop0:
 185         movea.l         a1,a0
 186         jsr             load_prepare
 187
 188         move.l          #64/2-1,d3
 189 0:      move.l          #0x00000000,(a0)
 190         dbra            d3,0b
 191
 192         add.l           #64*2,a1
 193         dbra            d4,lmaploop0
 194
 195         /* generate B layer map */
 196         movea.l         #0xc000,a0
 197         jsr             load_prepare
 198
 199         move.l          #64*28/2-1,d3
 200 0:      move.l          #0x00000000,(a0)
 201         dbra            d3,0b
 202
 203         /* upload sprite data */
 204         movea.l         #0xfc00,a0
 205         jsr             load_prepare
 206         movea.l         #sprite_data,a1
 207
 208         move.l          #(sprite_data_end-sprite_data)/2-1,d3
 209 0:      move.l          (a1)+,(a0)
 210         dbra            d3,0b
 211
 212         move.w          #0x2000,sr
 213
 214 ##################################################
 215 #                                                #
 216 #                 MAIN LOOP                      #
 217 #                                                #
 218 ##################################################
 219
 220 # global regs:
 221 # a6 = page_start[31:8]|cursor_offs[7:0]
 222 # d7 = old_inputs[31:16]|byte_mode[15]|g_mode[10:8]|irq_cnt[7:0]
 223 # d6 = autorep_cnt[3:0]
 224
 225 forever:
 226
 227
 228         jsr             wait_vsync
 229         bra             forever
 230
 231
 232
 233 VBL:
 234         addq.b          #1,d7
 235         movem.l         d0-d5/a0-a5,-(a7)
 236
 237         moveq.l         #0,d0
 238         move.w          d7,d0
 239         lsr.w           #6,d0
 240         and.w           #0x1c,d0
 241         move.l          (jumptab,pc,d0),a0
 242         jmp             (a0)
 243 jumptab:
 244         dc.l            mode_main
 245         dc.l            mode_edit
 246         dc.l            mode_main
 247         dc.l            mode_main
 248         dc.l            mode_main
 249         dc.l            mode_main
 250         dc.l            mode_main
 251         dc.l            mode_main
 252
 253 ##################### main #######################
 254
 255 mode_main:
 256         clr.l           d1
 257         move.l          a6,d0
 258         move.b          d0,d1
 259         lsr.l           #8,d0
 260         move.l          d0,a1           /* current addr */
 261         lsr.b           #3,d1
 262         neg.b           d1
 263         add.b           #27-1,d1        /* line where the cursor sits */
 264         swap            d1
 265
 266         movea.l         #0xe004,a2
 267         move.l          #27-1,d5        /* line counter for dbra */
 268         or.l            d1,d5
 269
 270 draw_column:
 271         move.l          a2,a0
 272         jsr             load_prepare
 273
 274         /* addr */
 275         move.l          a1,d2
 276         moveq.l         #6,d3
 277         jsr             print_hex_preped
 278
 279         /* 4 shorts */
 280         moveq.l         #4,d3
 281         moveq.l         #4-1,d4
 282 draw_shorts:
 283         move.w          #' ',(a0)
 284         move.w          (a1)+,d2
 285         jsr             print_hex_preped
 286         dbra            d4,draw_shorts
 287
 288         move.l          d5,d0
 289         swap            d0
 290         cmp.w           d5,d0
 291         beq             draw_cursor
 292
 293 draw_chars_pre:
 294         move.l          #(' '<<16)|' ',(a0)
 295
 296         /* 8 chars */
 297         subq.l          #8,a1
 298         moveq.l         #8-1,d4
 299 draw_chars:
 300         move.b          (a1)+,d0
 301         move.b          d0,d1
 302         sub.b           #0x20,d1
 303         cmp.b           #0x60,d1
 304         blo             0f
 305         move.w          #'.',d0
 306 0:
 307         move.w          d0,(a0)
 308         dbra            d4,draw_chars
 309
 310         add.w           #0x80,a2
 311         dbra            d5,draw_column
 312
 313         /* status bar */
 314         movea.l         #0xe004+64*2*27,a0
 315         jsr             load_prepare
 316         move.l          a6,d2
 317         moveq.l         #0,d3
 318         move.b          d2,d3
 319         lsr.l           #8,d2
 320         add.l           d3,d2
 321         move.l          #0x4006,d3
 322         jsr             print_hex_preped
 323
 324         /* handle input */
 325         jsr             get_input               /* x0cbrldu x1sa00du */
 326
 327         btst.l          #16+4,d0                /* A - scroll modifier */
 328         beq             input_noa
 329
 330         do_dpad         16+0,  sub, #0x0800
 331         do_dpad         16+1,  add, #0x0800
 332         do_dpad         16+10, sub, #0xd800
 333         do_dpad         16+11, add, #0xd800
 334 input_noa:
 335         moveq.l         #0,d1
 336         btst.l          #15,d7
 337         seq             d1
 338         neg.b           d1                      /* 1 if word sel */
 339         add.b           #1,d1
 340
 341         do_dpad         0,  subq, #0x0008
 342         do_dpad         1,  addq, #0x0008
 343         do_dpad         10, sub, d1
 344         do_dpad         11, add, d1
 345
 346 dpad_end:
 347         moveq.l         #0,d1
 348         btst.l          #12,d0                  /* B - switch byte/word mode */
 349         beq             input_nob
 350         bchg.l          #15,d7
 351         move.l          a6,d1
 352         and.l           #1,d1
 353         sub.l           d1,a6                   /* make even, just in case */
 354
 355 input_nob:
 356         btst.l          #13,d0                  /* C - edit selected byte */
 357         beq             input_noc
 358 #       and.w           #0xf8ff,d7
 359         or.w            #0x0100,d7              /* switch to edit mode */
 360         write_vdp_reg   12,(VDP12_SCREEN_V224 | VDP12_SCREEN_H320 | VDP12_STE)
 361
 362 input_noc:
 363         /* update addr */
 364         move.l          a6,d0
 365         cmp.b           #0xf0,d0
 366         blo             0f
 367         sub.l           #0xd800,a6
 368         add.w           #0x00d8,a6
 369         bra             1f
 370 0:
 371         cmp.b           #0xd8,d0
 372         blo             1f
 373         add.l           #0xd800,a6
 374         sub.w           #0x00d8,a6
 375 1:
 376
 377 vbl_end:
 378         movem.l         (a7)+,d0-d5/a0-a5
 379         rte
 380
 381
 382 draw_cursor:
 383         move.l          a6,d0
 384         and.l           #7,d0           /* byte offs */
 385         move.l          d0,d1
 386         lsr.b           #1,d1           /* which word */
 387         move.b          d1,d2
 388         lsl.b           #2,d2
 389         add.b           d2,d1           /* num of chars to skip */
 390         lsl.b           #1,d1
 391         move.w          #0x2004,d3
 392
 393         btst.l          #15,d7
 394         beq             draw_cursor_word
 395
 396 draw_cursor_byte:
 397         move.b          (-8,a1,d0),d2
 398         and.b           #1,d0
 399         lsl.b           #2,d0
 400         add.b           d0,d1
 401         subq.b          #2,d3
 402         bra             0f
 403
 404 draw_cursor_word:
 405         move.w          (-8,a1,d0),d2
 406 0:
 407         lea             (7*2,a2,d1),a0
 408         jsr             load_prepare
 409         jsr             print_hex_preped
 410
 411         move.l          a2,a0
 412         add.w           #26*2,a0
 413         jsr             load_prepare    /* restore a0 */
 414
 415         jmp             draw_chars_pre
 416
 417
 418 ##################### edit #######################
 419
 420 mode_edit:
 421         jmp             vbl_end
 422
 423
 424 #################################################
 425 #                                               #
 426 #         Initialize VDP registers              #
 427 #                                               #
 428 #################################################
 429
 430 init_gfx:
 431         move.l          #GFXCNTL,a3
 432         write_vdp_reg   0,(VDP0_E_DISPLAY | VDP0_PLTT_FULL)
 433         write_vdp_reg   1,(VDP1_E_VBI | VDP1_E_DISPLAY | VDP1_E_DMA | VDP1_RESERVED)
 434         write_vdp_reg   2,(0xe000 >> 10)        /* Screen map a adress */
 435         write_vdp_reg   3,(0xe000 >> 10)        /* Window address */
 436         write_vdp_reg   4,(0xc000 >> 13)        /* Screen map b address */
 437         write_vdp_reg   5,(0xfc00 >>  9)        /* Sprite address */
 438         write_vdp_reg   6,0
 439         write_vdp_reg   7,0                     /* Backdrop color */
 440         write_vdp_reg   10,1                    /* Lines per hblank interrupt */
 441         write_vdp_reg   11,0                    /* 2-cell vertical scrolling */
 442         write_vdp_reg   12,(VDP12_SCREEN_V224 | VDP12_SCREEN_H320)
 443         write_vdp_reg   13,(0x8000 >> 10)       /* Horizontal scroll address */
 444         write_vdp_reg   15,2
 445         write_vdp_reg   16,(VDP16_MAP_V32 | VDP16_MAP_H64)      /* layer size */
 446         write_vdp_reg   17,0
 447         write_vdp_reg   18,0xff
 448         rts
 449
 450
 451 # read single phase from controller
 452 #  #a0 - addr
 453 #  d0 - result
 454 #  destroys d1,d2
 455 get_input:
 456         move.b          #0x40,(0xa10003)
 457         nop
 458         nop
 459         nop
 460         move.b          (0xa10003),d0
 461         move.b          #0x00,(0xa10003)
 462         lsl.w           #8,d0
 463         nop
 464         move.b          (0xa10003),d0
 465         eor.w           #0xffff,d0
 466
 467         swap            d7
 468         move.w          d7,d1
 469         eor.w           d0,d1           /* changed btns */
 470         move.w          d0,d7           /* old val */
 471         swap            d7
 472         and.w           d0,d1           /* what changed now */
 473         bne             0f
 474
 475         addq.b          #1,d6
 476         move.b          d6,d2
 477         and.b           #7,d2           /* do autorepeat every 8 frames */
 478         cmp.b           #7,d2
 479         bne             1f
 480         move.w          d0,d1
 481 0:
 482         and.b           #0xf8,d6
 483 1:
 484         swap            d0
 485         move.w          d1,d0
 486         rts
 487
 488 # Load tile data from ROM
 489 #  a0: VRAM base
 490 #  a1: pattern address
 491 #  d0: number of tiles to load
 492 #  destroys d1
 493
 494 load_tiles:
 495         move.l          d0,d1
 496         VRAM_ADDR_var   a0
 497         move.l          d0,(GFXCNTL).l
 498
 499         move.l          #GFXDATA,a0
 500         lsl.w           #3,d1
 501         subq.l          #1,d1
 502 0:
 503         move.l          (a1)+,(a0)
 504         dbra            d1,0b
 505
 506         rts
 507
 508
 509 # Prepare to write to VDP RAM @a3
 510 # sets a0 to VDP data port for convenience
 511 #  a0: VRAM base
 512 #  destroys d0
 513
 514 load_prepare:
 515         VRAM_ADDR_var   a0
 516         move.l          d0,(GFXCNTL).l
 517         move.l          #GFXDATA,a0
 518         rts
 519
 520
 521 # Load color data from ROM
 522 #  a0: CRAM base
 523 #  a1: color list address
 524 #  d0: number of colors to load
 525 #  destroys d1
 526
 527 load_colors:
 528         move.l          d0,d1
 529         CRAM_ADDR_var   a0
 530         move.l          d0,(GFXCNTL).l
 531
 532         move.l          #GFXDATA,a0
 533         subq.w          #1,d1
 534 0:
 535         move.w          (a1)+,(a0)
 536         dbra            d1,0b
 537
 538         rts
 539
 540
 541 # print
 542 #  a0 - string
 543 #  d0 - x
 544 #  d1 - y
 545 #  destroys a1
 546
 547 print:
 548         move.l          a0,a1
 549         XY2NT
 550         jsr             load_prepare
 551         moveq.l         #0,d0
 552
 553 _print_loop:
 554         move.b          (a1)+,d0
 555         beq             _print_end
 556
 557         move.w          d0,(a0)
 558         jmp             _print_loop
 559
 560 _print_end:
 561         rts
 562
 563
 564 # print_hex
 565 #  d0 - x
 566 #  d1 - y
 567 #  d2 - value
 568 #  d3 - digit_cnt[0:7]|tile_bits[11:15]
 569 #  destroys a0, preserves d3
 570
 571 print_hex:
 572         XY2NT
 573         jsr             load_prepare
 574
 575 print_hex_preped:
 576         moveq.l         #0,d0
 577         move.b          d3,d0
 578         move.l          d0,d1
 579         lsl.b           #2,d0
 580         ror.l           d0,d2           /* prep value */
 581         subq.l          #1,d1           /* count */
 582         move.w          d3,d0
 583         and.w           #0xf800,d0      /* keep upper bits in d0 */
 584
 585 _print_hex_loop:
 586         rol.l           #4,d2
 587         move.b          d2,d0
 588         and.b           #0xf,d0
 589
 590         add.b           #'0',d0
 591         cmp.b           #'9',d0
 592         ble             0f
 593         addq.b          #7,d0
 594 0:
 595         move.w          d0,(a0)
 596         dbra            d1,_print_hex_loop
 597
 598         rts
 599
 600
 601 #################################################
 602 #                                               #
 603 #       Wait for next VBlank interrupt          #
 604 #                                               #
 605 #################################################
 606
 607 wait_vsync:
 608         move.b          d7,d0
 609 _wait_change:
 610         stop            #0x2000
 611         cmp.b           d7,d0
 612         beq             _wait_change
 613         rts
 614
 615
 616 #################################################
 617 #                                               #
 618 #                 RAM DATA                      #
 619 #                                               #
 620 #################################################
 621
 622 .bss
 623
 624 # nothing :)
 625
 626 .end
 627
 628 # vim:filetype=asmM68k