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ASHC v-flag

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Folkert van Heusden 2025-04-04 23:10:53 +02:00
parent a965b9ce7e
commit a6710ad0ff
Signed by untrusted user who does not match committer: folkert
GPG key ID: 6B6455EDFEED3BD1
2 changed files with 25 additions and 19 deletions
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37
cpu.cpp
View file

@ -786,7 +786,7 @@ bool cpu::additional_double_operand_instructions(const uint16_t instr)
return true;
}
else if (divider == -1 && uint32_t(R0R1) == 0x80000000) { // maximum negative value; too big
else if (divider == -1 && uint32_t(R0R1) == B32_MSBSET) { // maximum negative value; too big
setPSW_n(false);
setPSW_z(false);
setPSW_v(true);
@ -870,38 +870,43 @@ bool cpu::additional_double_operand_instructions(const uint16_t instr)
case 3: { // ASHC
uint32_t R0R1 = (uint32_t(get_register(reg)) << 16) | get_register(reg | 1);
bool sign = R0R1 & 0x80000000;
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;
TRACE("shift %012o (base-reg: R%d) with %d", R0R1, reg, shift);
setPSW_v(false);
if (shift == 0)
setPSW_c(false);
else if (shift < 32) {
R0R1 <<= shift - 1;
setPSW_c((R0R1 << (shift - 1)) & B32_MSBSET);
setPSW_c(R0R1 >> 31);
R0R1 <<= 1;
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) | 0xffffffff00000000ll) >> shift_n;
R0R1 = (uint64_t(R0R1) | B64_MSWSET) >> shift_n;
setPSW_c(R0R1 & 1);
R0R1 = (uint64_t(R0R1) | 0xffffffff00000000ll) >> 1;
R0R1 = (uint64_t(R0R1) | B64_MSWSET) >> 1;
}
else {
R0R1 >>= shift_n;
@ -910,15 +915,15 @@ bool cpu::additional_double_operand_instructions(const uint16_t instr)
R0R1 >>= 1;
}
bool new_sign = R0R1 & B32_MSBSET;
setPSW_v(sign != new_sign);
}
bool new_sign = R0R1 & 0x80000000;
setPSW_v(sign != new_sign);
set_register(reg, R0R1 >> 16);
set_register(reg, R0R1 >> 16 );
set_register(reg | 1, R0R1 & 65535);
setPSW_n(new_sign);
setPSW_n(R0R1 & B32_MSBSET);
setPSW_z(R0R1 == 0);
return true;

7
cpu.h
View file

@ -19,9 +19,10 @@
class breakpoint;
class bus;
constexpr const int initial_trap_delay = 8;
constexpr const int max_stacktrace_depth = 16;
constexpr const int initial_trap_delay = 8;
constexpr const int max_stacktrace_depth = 16;
constexpr const uint32_t B32_MSBSET = 0x80000000;
constexpr const uint64_t B64_MSWSET = 0xffffffff00000000ll;
typedef struct {
int delta;