1 /*****************************************************************************/
5 /* Memory subsystem for the 6502 simulator */
9 /* (C) 2002-2003 Ullrich von Bassewitz */
10 /* Römerstrasse 52 */
11 /* D-70794 Filderstadt */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
52 /*****************************************************************************/
54 /*****************************************************************************/
58 /* Pointer to our memory */
59 static const ChipInstance** MemData = 0;
64 /*****************************************************************************/
66 /*****************************************************************************/
70 void MemWriteByte (unsigned Addr, unsigned char Val)
71 /* Write a byte to a memory location */
73 /* Get the instance of the chip at this address */
74 const ChipInstance* CI = MemData[Addr];
76 /* Check if the memory is mapped */
78 Warning ("Writing to unassigned memory at $%06X", Addr);
80 CI->C->Data->Write (CI->Data, Addr - CI->Addr, Val);
86 unsigned char MemReadByte (unsigned Addr)
87 /* Read a byte from a memory location */
89 /* Get the instance of the chip at this address */
90 const ChipInstance* CI = MemData[Addr];
92 /* Check if the memory is mapped */
94 Warning ("Reading from unassigned memory at $%06X", Addr);
97 return CI->C->Data->Read (CI->Data, Addr - CI->Addr);
103 unsigned MemReadWord (unsigned Addr)
104 /* Read a word from a memory location */
106 unsigned W = MemReadByte (Addr++);
107 return (W | (MemReadByte (Addr) << 8));
112 unsigned MemReadZPWord (unsigned char Addr)
113 /* Read a word from the zero page. This function differs from ReadMemW in that
114 * the read will always be in the zero page, even in case of an address
118 unsigned W = MemReadByte (Addr++);
119 return (W | (MemReadByte (Addr) << 8));
124 void MemAssignChip (const ChipInstance* CI, unsigned Addr, unsigned Range)
125 /* Assign a chip instance to memory locations */
127 /* Make sure, the addresses are in a valid range */
128 PRECONDITION (Addr + Range <= MemSize);
130 /* Assign the chip instance */
132 CHECK (MemData[Addr] == 0);
133 MemData[Addr++] = CI;
139 const struct ChipInstance* MemGetChip (unsigned Addr)
140 /* Get the chip that is located at the given address (may return NULL). */
142 /* Make sure, the address is valid */
143 PRECONDITION (Addr < MemSize);
145 /* Return the chip instance */
146 return MemData[Addr];
152 /* Initialize the memory subsystem */
156 /* Allocate memory depending on the CPU type */
163 Internal ("Unexpected CPU type: %d", CPU);
165 MemData = xmalloc (MemSize * sizeof (ChipInstance*));
167 /* Clear the memory */
168 for (I = 0; I < MemSize; ++I) {