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atirage: Implement reads/writes from/to the auxiliary aperture #162

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Merged
dingusdev merged 4 commits into from
Feb 4, 2026
Merged

atirage: Implement reads/writes from/to the auxiliary aperture #162

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7c29e41
atirage: Definitions for auxiliary register aperture
Cacodemon345 Feb 4, 2026
6a3654e
atirage: Implement reads/writes from the auxiliary aperture
Cacodemon345 Feb 4, 2026
4c3989f
atirage: Remove unreachable logging for auxiliary aperture
Cacodemon345 Feb 4, 2026
7abc8af
atirage: Remove more redundant code
Cacodemon345 Feb 4, 2026
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4 changes: 4 additions & 0 deletions devices/video/atimach64defs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -692,6 +692,10 @@ constexpr auto MM_REGS_0_OFF = 0x007FFC00U; // offset to memory mapped registers
constexpr auto MM_REGS_1_OFF = 0x007FF800U; // offset to memory mapped registers, block 1
constexpr auto MM_REGS_2_OFF = 0x003FFC00U; // offset to memory mapped registers, 4MB aperture

// Auxiliary register aperture.
constexpr auto MM_STDL_REGS_0_OFF = 0x400U; // offset to memory mapped registers, block 0
constexpr auto MM_STDL_REGS_1_OFF = 0x000U; // offset to memory mapped registers, block 1

constexpr auto ATI_XTAL = 14318180.0f; // external crystal oscillator frequency

#endif // ATI_MACH64_DEFS_H
22 changes: 16 additions & 6 deletions devices/video/atirage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -627,9 +627,16 @@ uint32_t ATIRage::read(uint32_t rgn_start, uint32_t offset, int size)
}

if (rgn_start == this->aperture_base[2] && offset < this->aperture_size[2]) {
LOG_F(WARNING, "%s: read unmapped aperture[2] region %08x.%c",
this->name.c_str(), offset, SIZE_ARG(size));
return 0;
// The documentation for the Rage LT Pro marks the upper 2KB
// of the 4KB aux. aperture reserved, but it's used by Mac OS
// anyway for Rage II. Make it wrap around the 2KB boundary
// instead.
offset &= 0x7ff;
if (offset >= MM_STDL_REGS_0_OFF) {
return BYTESWAP_SIZED(this->read_reg(offset & 0x3FF, size), size);
}
// Rest of the region is Block 1.
return BYTESWAP_SIZED(this->read_reg((offset & 0x3FF) + 0x400, size), size);
}

// memory mapped expansion ROM region
Expand Down Expand Up @@ -674,9 +681,12 @@ void ATIRage::write(uint32_t rgn_start, uint32_t offset, uint32_t value, int siz
}

if (rgn_start == this->aperture_base[2] && offset < this->aperture_size[2]) {
LOG_F(WARNING, "%s: write unmapped aperture[2] region %08x.%c = %0*x",
this->name.c_str(), offset, SIZE_ARG(size), size * 2, value);
return;
// See the note about wrap around above.
offset &= 0x7ff;
if (offset >= MM_STDL_REGS_0_OFF) {
return this->write_reg(offset & 0x3FF, BYTESWAP_SIZED(value, size), size);
}
return this->write_reg((offset & 0x3FF) + 0x400, BYTESWAP_SIZED(value, size), size);
}

LOG_F(WARNING, "%s: write unmapped aperture region %08x.%c = %0*x",
Expand Down