/* * vic-mem.c - Memory interface for the VIC-I emulation. * * Written by * Ettore Perazzoli * Andreas Matthies * Daniel Kahlin * * This file is part of VICE, the Versatile Commodore Emulator. * See README for copyright notice. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA * 02111-1307 USA. * */ #include "vice.h" #include #include #include #include "joyport.h" #include "lib.h" #include "maincpu.h" #include "raster-changes.h" #include "types.h" #include "vic.h" #include "victypes.h" #include "vic-mem.h" #include "vic20.h" #include "vic20mem.h" #include "vic20sound.h" #include "viewport.h" #ifdef HAVE_MOUSE #include "lightpen.h" #include "mouse.h" static CLOCK pot_cycle = 0; /* pot sampling cycle */ #endif /* VIC access functions. */ void vic_store(uint16_t addr, uint8_t value) { addr &= 0xf; vic.regs[addr] = value; VIC_DEBUG_REGISTER (("VIC: write $90%02X, value = $%02X.", addr, value)); switch (addr) { #if 0 /* handled in vic_cycle.c */ case 0: /* $9000 Screen X Location. */ /* VIC checks in cycle n for peek($9000)=n and in this case opens the horizontal flipflop */ case 1: /* $9001 Screen Y Location. */ /* VIC checks from cycle 1 of line r*2 to cycle 0 of line r*2+2 if peek($9001)=r is true and in this case it opens the vertical flipflop */ case 2: /* $9002 Columns Displayed. */ case 5: /* $9005 Video and char matrix base address. */ /* read-only registers */ case 4: /* $9004 Raster line count -- read only. */ case 6: /* $9006. */ case 7: /* $9007 Light Pen X,Y. */ case 8: /* $9008. */ case 9: /* $9009 Paddle X,Y. */ #endif default: return; case 3: /* $9003 Rows Displayed, Character size . */ { int new_char_height = (value & 0x1) ? 16 : 8; vic.row_increase_line = new_char_height; vic.char_height = new_char_height; } return; case 10: /* $900A Bass Enable and Frequency. */ case 11: /* $900B Alto Enable and Frequency. */ case 12: /* $900C Soprano Enable and Frequency. */ case 13: /* $900D Noise Enable and Frequency. */ vic_sound_store(addr, value); return; case 14: /* $900E Auxiliary Colour, Master Volume. */ /* changes of auxiliary color in cycle n is visible at pixel 4*(n-7)+1 */ { static int old_aux_color = -1; int new_aux_color = value >> 4; if (new_aux_color != old_aux_color) { /* integer part */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.auxiliary_color, new_aux_color); /* fractional part (half chars) */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.half_char_flag, VIC_RASTER_CHAR_FRAC(vic.raster_cycle + 1)); /* old_mc_auxilary_color is used by vic-draw.c to handle the one hires vic pixel lateness of change */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR(vic.raster_cycle + 2), &vic.old_auxiliary_color, new_aux_color); old_aux_color = new_aux_color; } } vic_sound_store(addr, value); return; case 15: /* $900F Screen and Border Colors, Reverse Video. */ /* changes of border/background in cycle n are visible at pixel 4*(n-7)+1, changes of reverse mode at pixel 4*(n-7)+3. */ { static int old_background_color = -1; static int old_border_color = -1; static int old_reverse = -1; int new_background_color, new_border_color, new_reverse; new_background_color = value >> 4; new_border_color = value & 0x7; new_reverse = ((value & 0x8) ? 0 : 1); if (new_background_color != old_background_color) { raster_changes_background_add_int(&vic.raster, VIC_RASTER_X(vic.raster_cycle + 1) + VIC_PIXEL_WIDTH, (int*)&vic.raster.background_color, new_background_color); old_background_color = new_background_color; } if (new_border_color != old_border_color) { raster_changes_border_add_int(&vic.raster, VIC_RASTER_X(vic.raster_cycle + 1) + VIC_PIXEL_WIDTH, (int*)&vic.raster.border_color, new_border_color); /* we also need the border color in multicolor mode, so we duplicate it */ /* integer part */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.mc_border_color, new_border_color); /* fractional part (half chars) */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.half_char_flag, VIC_RASTER_CHAR_FRAC(vic.raster_cycle + 1)); } if (new_reverse != old_reverse) { /* integer part */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.reverse, new_reverse); /* fractional part (half chars) */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR_INT(vic.raster_cycle + 1), &vic.half_char_flag, VIC_RASTER_CHAR_FRAC(vic.raster_cycle + 1)); } if (new_border_color != old_border_color) { /* old_mc_border_color is used by vic-draw.c to handle the one hires vic pixel lateness of change */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR(vic.raster_cycle + 2), &vic.old_mc_border_color, new_border_color); old_border_color = new_border_color; } if (new_reverse != old_reverse) { /* old_reverse is used by vic-draw.c to handle the 3 hires vic pixels lateness of change */ raster_changes_foreground_add_int(&vic.raster, VIC_RASTER_CHAR(vic.raster_cycle + 2), &vic.old_reverse, new_reverse); old_reverse = new_reverse; } return; } } } static inline unsigned vic_read_rasterline(void) { unsigned ypos = VIC_RASTER_Y(maincpu_clk + vic.cycle_offset); /* TODO: examine/verify what exactly happens, and in what cycles. the over- * all frame timing must be correct (as hardcoded timer values in * games work) so the only way it makes sense is that when rasterline 0 * is "shorter", the last rasterline has to be "longer". */ if (vic.cycles_per_line == VIC20_NTSC_CYCLES_PER_LINE) { if (vic.interlace_enabled) { /* FIXME: unfortunately using this for the VIC_RASTER_Y macro breaks non interlaced timing and perhaps also PAL - we need to investigate this further */ ypos = ((unsigned int)(((maincpu_clk + vic.cycle_offset) - vic.framestart_cycle) / 65)); /* interlaced top + bottom field combined cycle count: 32+262x65 + 262x65+33 = 525x65 cycles */ if (vic.interlace_field == 0) { /* * top * line 0 with 32 cycles lines 1..262 with 65 cycles */ /* HACK: the cycle offset pushes ypos to last+1, this is part of line 0 of the next field */ if (ypos >= (VIC20_NTSC_INTERLACE_FIELD1_LAST_LINE + 1)) { return 0; } } else { /* * bottom * lines 0..261 with 65 cycles line 262 with 33 cycles */ /* HACK: the last line of this field and the first line of the other field add up to a full line */ if (ypos >= VIC20_NTSC_INTERLACE_FIELD2_LAST_LINE) { if (VIC_RASTER_CYCLE(maincpu_clk + vic.cycle_offset) < VIC20_NTSC_INTERLACE_FIELD2_CYCLES_LAST_LINE) { return VIC20_NTSC_INTERLACE_FIELD2_LAST_LINE; /* confirm this */ } else { return 0; } } } return ypos; } else { /* no interlace */ /* line 0 with 32 cycles lines 1..260 with 65 cycles line 261 with 33 cycles total number: 32+260x65+33 = 261x65 cycles HACK: we fake this by returning line=261 for the first 33 cycles of line 0 */ if (ypos == 0) { if (VIC_RASTER_CYCLE(maincpu_clk + vic.cycle_offset) < VIC20_NTSC_CYCLES_LAST_LINE) { return VIC20_NTSC_LAST_LINE; /* confirm this */ } } } } return ypos; } /* Add some randomness to the pot value(s). Note that _with paddles_ the error gets gradually worse depending on the sampled value (the larger the value, the bigger error. This does _not_ happen with the 1351 mouse. Additionally the amount of error appears to depend on display DMA. */ static inline uint8_t makepotval(int value) { unsigned int fuzz; if (get_joyport_pot_type() == JOYPORT_POT_TYPE_ANALOG) { if (vic.area == VIC_AREA_DISPLAY) { fuzz = lib_unsigned_rand(0, 1 + ((value * 25) / 255)); } else { fuzz = lib_unsigned_rand(0, 1 + ((value * 5) / 255)); } } else { fuzz = lib_unsigned_rand(0, 1); } value += fuzz; if (value > 255) { return 255; } return value; } uint8_t vic_read(uint16_t addr) { addr &= 0xf; #ifdef HAVE_MOUSE if ((addr == 8) || (addr == 9)) { if ((maincpu_clk ^ pot_cycle) & ~511) { pot_cycle = maincpu_clk & ~511; /* simplistic 512 cycle sampling */ if (_mouse_enabled) { mouse_poll(); } vic.regs[8] = makepotval(read_joyport_potx()); vic.regs[9] = makepotval(read_joyport_poty()); } } #endif switch (addr) { case 3: return ((vic_read_rasterline() & 1) << 7) | (vic.regs[3] & ~0x80); case 4: return vic_read_rasterline() >> 1; case 6: return vic.light_pen.x; case 7: return vic.light_pen.y; default: return vic.regs[addr]; } } uint8_t vic_peek(uint16_t addr) { /* No side effects (unless mouse_get_* counts) */ return vic_read(addr); }