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ASH/ASHC cleanup & fix

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Folkert van Heusden 2025-04-05 11:44:27 +02:00
parent 8e9c4d3eb0
commit 1a8a239f19
Signed by untrusted user who does not match committer: folkert
GPG key ID: 6B6455EDFEED3BD1
2 changed files with 69 additions and 98 deletions
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157
cpu.cpp
View file

@ -1,4 +1,4 @@
// (C) 2018-2024 by Folkert van Heusden
// (C) 2018-2025 by Folkert van Heusden
// Released under MIT license
#include <assert.h>
@ -741,6 +741,59 @@ bool cpu::double_operand_instructions(const uint16_t instr)
return false;
}
uint32_t cpu::shifter(uint32_t value, int shift, bool is32b)
{
uint64_t sign_extend = is32b ? B64_MSWSET : (B64_MSWSET | B32_MSWSET);
uint32_t sign_mask = is32b ? B32_MSBSET : B16_MSBSET;
uint32_t mask = is32b ? 0xffffffff : 0xffff;
bool sign = value & sign_mask;
TRACE("shift %012o with %d", value, shift);
setPSW_v(false);
if (shift == 0)
setPSW_c(false);
else if (shift < 32) {
setPSW_c((value << (shift - 1)) & sign_mask);
for(int i=0; i<shift; i++) {
value <<= 1;
if (bool(value & sign_mask) != sign)
setPSW_v(true);
}
}
else if (shift == 32) {
value = -sign;
setPSW_c(sign);
setPSW_v(sign != bool(value & sign_mask));
}
else {
int shift_n = (64 - shift) - 1;
// extend sign-bit
if (sign) { // convert to unsigned 64b int & extend sign
value = (uint64_t(value) | sign_extend) >> shift_n;
setPSW_c(value & 1);
value = (uint64_t(value) | sign_extend) >> 1;
}
else {
value >>= shift_n;
setPSW_c(value & 1);
value >>= 1;
}
bool new_sign = value & sign_mask;
setPSW_v(sign != new_sign);
}
value &= mask;
setPSW_n(value & sign_mask);
setPSW_z(value == 0);
return value;
}
bool cpu::additional_double_operand_instructions(const uint16_t instr)
{
const uint8_t reg = (instr >> 6) & 7;
@ -817,114 +870,28 @@ bool cpu::additional_double_operand_instructions(const uint16_t instr)
}
case 2: { // ASH
uint32_t R = get_register(reg), oldR = R;
uint32_t R = get_register(reg);
auto g_dst = getGAM(dst_mode, dst_reg, wm_word);
addToMMR1(g_dst);
uint16_t shift = g_dst.value.value() & 077;
int shift = g_dst.value.value() & 077;
TRACE("shift %06o with %d", R, shift);
uint32_t new_value = shifter(R, shift, false);
bool sign = SIGN(R, wm_word);
if (shift == 0) {
setPSW_c(false);
setPSW_v(false);
}
else if (shift < 32) {
if (shift > 15)
setPSW_c((R << (shift - 16)) & 1);
setPSW_v(false);
for(int i=0; i<shift; i++) {
R <<= 1;
if (SIGN(R, wm_word) != sign)
setPSW_v(true);
}
if (shift <= 15)
setPSW_c(R & 0x10000);
}
else if (shift == 32) {
R = -sign;
setPSW_c(sign);
setPSW_v(SIGN(oldR, wm_word) != SIGN(R, wm_word));
}
else {
int shift_n = 64 - shift;
uint32_t sign_extend = sign ? 0x8000 : 0;
for(int i=0; i<shift_n; i++) {
setPSW_c(R & 1);
R >>= 1;
R |= sign_extend;
}
}
setPSW_n(SIGN(R, wm_word));
setPSW_z((R & 0xffff) == 0);
set_register(reg, R);
set_register(reg, new_value);
return true;
}
case 3: { // ASHC
uint32_t R0R1 = (uint32_t(get_register(reg)) << 16) | get_register(reg | 1);
bool sign = R0R1 & B32_MSBSET;
auto g_dst = getGAM(dst_mode, dst_reg, wm_word);
addToMMR1(g_dst);
uint16_t shift = g_dst.value.value() & 077;
int shift = g_dst.value.value() & 077;
TRACE("shift %012o (base-reg: R%d) with %d", R0R1, reg, shift);
uint32_t new_value = shifter(R0R1, shift, true);
setPSW_v(false);
if (shift == 0)
setPSW_c(false);
else if (shift < 32) {
setPSW_c((R0R1 << (shift - 1)) & B32_MSBSET);
setPSW_v(false);
for(int i=0; i<shift; i++) {
R0R1 <<= 1;
if (bool(R0R1 & B32_MSBSET) != sign)
setPSW_v(true);
}
}
else if (shift == 32) {
R0R1 = -sign;
setPSW_c(sign);
bool new_sign = R0R1 & B32_MSBSET;
setPSW_v(sign != new_sign);
}
else {
int shift_n = (64 - shift) - 1;
// extend sign-bit
if (sign) { // convert to unsigned 64b int & extend sign
R0R1 = (uint64_t(R0R1) | B64_MSWSET) >> shift_n;
setPSW_c(R0R1 & 1);
R0R1 = (uint64_t(R0R1) | B64_MSWSET) >> 1;
}
else {
R0R1 >>= shift_n;
setPSW_c(R0R1 & 1);
R0R1 >>= 1;
}
bool new_sign = R0R1 & B32_MSBSET;
setPSW_v(sign != new_sign);
}
set_register(reg, R0R1 >> 16 );
set_register(reg | 1, R0R1 & 65535);
setPSW_n(R0R1 & B32_MSBSET);
setPSW_z(R0R1 == 0);
set_register(reg, new_value >> 16 );
set_register(reg | 1, new_value & 65535);
return true;
}

4
cpu.h
View file

@ -21,7 +21,9 @@ class bus;
constexpr const int initial_trap_delay = 8;
constexpr const int max_stacktrace_depth = 16;
constexpr const uint16_t B16_MSBSET = 0x8000;
constexpr const uint32_t B32_MSBSET = 0x80000000;
constexpr const uint32_t B32_MSWSET = 0xffff0000;
constexpr const uint64_t B64_MSWSET = 0xffffffff00000000ll;
typedef struct {
@ -84,6 +86,8 @@ private:
bool check_pending_interrupts() const; // needs the 'qi_lock'-lock
bool execute_any_pending_interrupt();
uint32_t shifter(uint32_t value, int shift, bool is32b);
uint16_t add_register(const int nr, const uint16_t value);
void addToMMR1(const gam_rc_t & g);