2 // This file is part of the PicoDrive Megadrive Emulator
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4 // Copyright (c) 2011 FinalDave (emudave (at) gmail.com)
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6 // This code is licensed under the GNU General Public License version 2.0 and the MAME License.
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7 // You can choose the license that has the most advantages for you.
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9 // SVN repository can be found at http://code.google.com/p/cyclone68000/
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11 #include "PicoInt.h"
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13 static void Byteswap(unsigned char *data,int len)
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17 if (len<2) return; // Too short
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21 unsigned short *pd=(unsigned short *)(data+i);
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22 int value=*pd; // Get 2 bytes
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24 value=(value<<8)|(value>>8); // Byteswap it
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25 *pd=(unsigned short)value; // Put 2b ytes
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31 // Interleve a 16k block and byteswap
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32 static int InterleveBlock(unsigned char *dest,unsigned char *src)
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35 for (i=0;i<0x2000;i++) dest[(i<<1) ]=src[ i]; // Odd
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36 for (i=0;i<0x2000;i++) dest[(i<<1)+1]=src[0x2000+i]; // Even
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40 // Decode a SMD file
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41 static int DecodeSmd(unsigned char *data,int len)
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43 unsigned char *temp=NULL;
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46 temp=(unsigned char *)malloc(0x4000);
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47 if (temp==NULL) return 1;
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48 memset(temp,0,0x4000);
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50 // Interleve each 16k block and shift down by 0x200:
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51 for (i=0; i+0x4200<=len; i+=0x4000)
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53 InterleveBlock(temp,data+0x200+i); // Interleve 16k to temporary buffer
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54 memcpy(data+i,temp,0x4000); // Copy back in
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61 int PicoCartLoad(FILE *f,unsigned char **prom,unsigned int *psize)
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63 unsigned char *rom=NULL; int size=0;
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64 if (f==NULL) return 1;
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66 fseek(f,0,SEEK_END); size=ftell(f); fseek(f,0,SEEK_SET);
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68 size=(size+3)&~3; // Round up to a multiple of 4
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70 // Allocate space for the rom plus padding
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71 rom=(unsigned char *)malloc(size+4);
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72 if (rom==NULL) { fclose(f); return 1; }
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73 memset(rom,0,size+4);
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75 fread(rom,1,size,f); // Load up the rom
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79 if ((size&0x3fff)==0x200) { DecodeSmd(rom,size); size-=0x200; } // Decode and byteswap SMD
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80 else Byteswap(rom,size); // Just byteswap
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82 if (prom) *prom=rom;
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83 if (psize) *psize=size;
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88 // Insert/remove a cartridge:
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89 int PicoCartInsert(unsigned char *rom,unsigned int romsize)
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91 // Make sure movie playing/recording is stopped:
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92 if (PmovFile) fclose(PmovFile);
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93 PmovFile=NULL; PmovAction=0;
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95 memset(&Pico,0,sizeof(Pico)); // Blank Pico state
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97 Pico.romsize=romsize;
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