hw.c

   1 #include <string.h>
   2
   3
   4 #include "defs.h"
   5 #include "cpu.h"
   6 #include "hw.h"
   7 #include "regs.h"
   8 #include "lcd.h"
   9 #include "mem.h"
  10 #include "fastmem.h"
  11
  12
  13 struct hw hw;
  14
  15
  16
  17 /*
  18  * hw_interrupt changes the virtual interrupt lines included in the
  19  * specified mask to the values the corresponding bits in i take, and
  20  * in doing so, raises the appropriate bit of R_IF for any interrupt
  21  * lines that transition from low to high.
  22  */
  23
  24 void hw_interrupt(byte i, byte mask)
  25 {
  26         byte oldif = R_IF;
  27         i &= 0x1F & mask;
  28         R_IF |= i & (hw.ilines ^ i);
  29
  30         /* FIXME - is this correct? not sure the docs understand... */
  31         if ((R_IF & (R_IF ^ oldif) & R_IE) && cpu.ime) cpu.halt = 0;
  32         /* if ((i & (hw.ilines ^ i) & R_IE) && cpu.ime) cpu.halt = 0; */
  33         /* if ((i & R_IE) && cpu.ime) cpu.halt = 0; */
  34
  35         hw.ilines &= ~mask;
  36         hw.ilines |= i;
  37 }
  38
  39
  40 /*
  41  * hw_dma performs plain old memory-to-oam dma, the original dmg
  42  * dma. Although on the hardware it takes a good deal of time, the cpu
  43  * continues running during this mode of dma, so no special tricks to
  44  * stall the cpu are necessary.
  45  */
  46
  47 void hw_dma(byte b)
  48 {
  49         int i;
  50         addr a;
  51
  52         a = ((addr)b) << 8;
  53         for (i = 0; i < 160; i++, a++)
  54                 lcd.oam.mem[i] = readb(a);
  55 }
  56
  57
  58
  59 void hw_hdma_cmd(byte c)
  60 {
  61         int cnt;
  62         addr sa;
  63         int da;
  64
  65         /* Begin or cancel HDMA */
  66         if ((hw.hdma|c) & 0x80)
  67         {
  68                 hw.hdma = c;
  69                 R_HDMA5 = c & 0x7f;
  70                 return;
  71         }
  72
  73         /* Perform GDMA */
  74         sa = ((addr)R_HDMA1 << 8) | (R_HDMA2&0xf0);
  75         da = 0x8000 | ((int)(R_HDMA3&0x1f) << 8) | (R_HDMA4&0xf0);
  76         cnt = ((int)c)+1;
  77         /* FIXME - this should use cpu time! */
  78         /*cpu_timers(102 * cnt);*/
  79         cnt <<= 4;
  80         while (cnt--)
  81                 writeb(da++, readb(sa++));
  82         R_HDMA1 = sa >> 8;
  83         R_HDMA2 = sa & 0xF0;
  84         R_HDMA3 = 0x1F & (da >> 8);
  85         R_HDMA4 = da & 0xF0;
  86         R_HDMA5 = 0xFF;
  87 }
  88
  89
  90 void hw_hdma()
  91 {
  92         int cnt;
  93         addr sa;
  94         int da;
  95
  96         sa = ((addr)R_HDMA1 << 8) | (R_HDMA2&0xf0);
  97         da = 0x8000 | ((int)(R_HDMA3&0x1f) << 8) | (R_HDMA4&0xf0);
  98         cnt = 16;
  99         while (cnt--)
 100                 writeb(da++, readb(sa++));
 101         R_HDMA1 = sa >> 8;
 102         R_HDMA2 = sa & 0xF0;
 103         R_HDMA3 = 0x1F & (da >> 8);
 104         R_HDMA4 = da & 0xF0;
 105         R_HDMA5--;
 106         hw.hdma--;
 107 }
 108
 109
 110 /*
 111  * pad_refresh updates the P1 register from the pad states, generating
 112  * the appropriate interrupts (by quickly raising and lowering the
 113  * interrupt line) if a transition has been made.
 114  */
 115
 116 void pad_refresh()
 117 {
 118         byte oldp1;
 119         oldp1 = R_P1;
 120         R_P1 &= 0x30;
 121         R_P1 |= 0xc0;
 122         if (!(R_P1 & 0x10))
 123                 R_P1 |= (hw.pad & 0x0F);
 124         if (!(R_P1 & 0x20))
 125                 R_P1 |= (hw.pad >> 4);
 126         R_P1 ^= 0x0F;
 127         if (oldp1 & ~R_P1 & 0x0F)
 128         {
 129                 hw_interrupt(IF_PAD, IF_PAD);
 130                 hw_interrupt(0, IF_PAD);
 131         }
 132 }
 133
 134
 135 /*
 136  * These simple functions just update the state of a button on the
 137  * pad.
 138  */
 139
 140 void pad_press(byte k)
 141 {
 142         if (hw.pad & k)
 143                 return;
 144         hw.pad |= k;
 145         pad_refresh();
 146 }
 147
 148 void pad_release(byte k)
 149 {
 150         if (!(hw.pad & k))
 151                 return;
 152         hw.pad &= ~k;
 153         pad_refresh();
 154 }
 155
 156 void pad_set(byte k, int st)
 157 {
 158         st ? pad_press(k) : pad_release(k);
 159 }
 160
 161 void hw_reset()
 162 {
 163         hw.ilines = hw.pad = 0;
 164
 165         memset(ram.hi, 0, sizeof ram.hi);
 166
 167         R_P1 = 0xFF;
 168         R_LCDC = 0x91;
 169         R_BGP = 0xFC;
 170         R_OBP0 = 0xFF;
 171         R_OBP1 = 0xFF;
 172         R_SVBK = 0x01;
 173         R_HDMA5 = 0xFF;
 174         R_VBK = 0xFE;
 175 }
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