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virtual memory addressing clean-up

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folkert van heusden 2022-03-22 09:23:31 +01:00
parent 1a3bc28d95
commit c62fad55d0
1 changed files with 15 additions and 22 deletions
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37
bus.cpp
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@ -301,21 +301,18 @@ uint16_t bus::read(const uint16_t a, const bool word_mode, const bool use_prev)
} }
const uint8_t apf = a >> 13; // active page field const uint8_t apf = a >> 13; // active page field
bool is_user = use_prev ? (c -> getBitPSW(12) && c -> getBitPSW(13)) : (c -> getBitPSW(14) && c -> getBitPSW(15));
// always retrieve interrupt etc vectors from kernel space if (a < 01000)
if (a < 256 * 4) run_mode = 0;
is_user = false;
uint32_t m_offset = pages[run_mode][apf + is_user * 8].par * 64; uint32_t m_offset = pages[run_mode][apf].par * 64;
if ((a & 1) && word_mode == 0) m_offset += a & 8191;
D(fprintf(stderr, "odd addressing\n");)
if (!word_mode) if (word_mode)
temp = m -> readWord(m_offset + (a & 8191)); temp = m -> readByte(m_offset);
else else
temp = m -> readByte(m_offset + (a & 8191)); temp = m -> readWord(m_offset);
return temp; return temp;
} }
@ -325,9 +322,8 @@ uint32_t bus::calculate_full_address(const uint16_t a)
const uint8_t apf = a >> 13; // active page field const uint8_t apf = a >> 13; // active page field
int run_mode = c->getPSW() >> 14; int run_mode = c->getPSW() >> 14;
bool is_user = run_mode == 3;
uint32_t m_offset = pages[run_mode][apf + is_user * 8].par * 64; uint32_t m_offset = pages[run_mode][apf].par * 64;
return m_offset + (a & 8191); return m_offset + (a & 8191);
} }
@ -568,23 +564,20 @@ uint16_t bus::write(const uint16_t a, const bool word_mode, uint16_t value, cons
} }
const uint8_t apf = a >> 13; // active page field const uint8_t apf = a >> 13; // active page field
bool is_user = use_prev ? (c -> getBitPSW(12) && c -> getBitPSW(13)) : (c -> getBitPSW(14) && c -> getBitPSW(15));
uint32_t m_offset = pages[run_mode][apf + is_user * 8].par * 64;
// always write interrupt etc vectors from to kernel space if (a < 01000)
// TODO: check rights run_mode = 0;
if (a < 256 * 4)
is_user = false; uint32_t m_offset = pages[run_mode][apf].par * 64;
pages[run_mode][apf].pdr |= 1 << 6; // page has been written to pages[run_mode][apf].pdr |= 1 << 6; // page has been written to
if ((a & 1) && word_mode == 0) m_offset += a & 8191;
D(fprintf(stderr, "odd addressing\n");)
if (word_mode) if (word_mode)
m -> writeByte(m_offset + (a & 8191), value); m -> writeByte(m_offset, value);
else else
m -> writeWord(m_offset + (a & 8191), value); m -> writeWord(m_offset, value);
return value; return value;
} }