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far model relocation

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This commit is contained in:
Kelvin Sherlock 2013-08-15 23:40:08 -04:00
parent 88423bc690
commit 4041b14b36
1 changed files with 71 additions and 1 deletions
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72
bin/loader.cpp
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@ -130,7 +130,67 @@ void WriteLong(void *data, uint32_t offset, uint32_t value)
((uint8_t *)data)[offset++] = value;
}
void reloc1(const uint8_t *r, uint32_t address, uint32_t offset)
{
// %00000000 00000000 -> break
// %0xxxxxxx -> 7-bit value
// %1xxxxxxx xxxxxxxx -> 15-bit value
// %00000000 1xxxxxxx x{8} x{8} x{8} -> 31 bit value
// ^ that's what the documentation says..
// that's how the 32-bit bootstrap works
// DumpCode ignores the high 2 bytes.
for(;;)
{
uint32_t x;
uint32_t value;
x = *r++;
if (x == 0x00)
{
x = *r++;
if (x == 0x00) break;
x = (x << 8) | *r++;
x = (x << 8) | *r++;
x = (x << 8) | *r++;
}
else if (x & 0x80)
{
x &= 0x7f;
x = (x << 8) | *r++;
}
x <<= 1; // * 2
address += x;
value = memoryReadLong(address);
memoryWriteLong(value + offset, address);
}
}
// relocate a far model segment.
void relocate(uint32_t address, uint32_t size, uint32_t a5)
{
// see MacOS RT Architecture, 10-23 .. 10-26
uint32_t offset;
offset = memoryReadLong(address + 0x14);
if (memoryReadLong(address + 0x18) != a5 && offset != 0)
{
memoryWriteLong(a5, address + 0x18); // current value of A5
reloc1(memoryPointer(address + offset), address, a5);
}
offset = memoryReadLong(address + 0x1c);
if (memoryReadLong(address + 0x20) != address && offset != 0)
{
memoryWriteLong(address, address + 0x20); // segment load address.
reloc1(memoryPointer(address + offset), address, address + 0x28);
}
}
uint32_t load(const char *file)
{
@ -302,7 +362,7 @@ uint32_t load(const char *file)
assert(offset < p.size);
// +$4/$28 for the jump table info header.
uint32_t address = p.address + offset + (p.farModel ? 0x28 : 0x04);
uint32_t address = p.address + offset + (p.farModel ? 0x00 : 0x04); // was 0x28
// JMP absolute long
memoryWriteWord(0x4EF9, jtStart + 2);
@ -316,6 +376,16 @@ uint32_t load(const char *file)
}
}
// far-model relocation. This happens here, after a5 is loaded.
for (const auto &seg : segments)
{
if (seg.farModel)
{
relocate(seg.address, seg.size, a5);
}
}
// set pc to jump table entry 0.
return returnAddress;