72 lines
1.8 KiB
C++
72 lines
1.8 KiB
C++
#include "alu.hh"
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#include "util/bits.hh"
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namespace matar {
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uint32_t
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eval_shift(ShiftType shift_type, uint32_t value, uint8_t amount, bool& carry) {
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uint32_t eval = 0;
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switch (shift_type) {
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case ShiftType::LSL:
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if (amount > 0 && amount <= 32)
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carry = get_bit(value, 32 - amount);
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else if (amount > 32)
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carry = 0;
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eval = value << amount;
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break;
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case ShiftType::LSR:
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if (amount > 0 && amount <= 32)
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carry = get_bit(value, amount - 1);
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else if (amount > 32)
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carry = 0;
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else
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carry = get_bit(value, 31);
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eval = value >> amount;
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break;
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case ShiftType::ASR:
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if (amount > 0 && amount <= 32)
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carry = get_bit(value, amount - 1);
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else
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carry = get_bit(value, 31);
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return static_cast<int32_t>(value) >> amount;
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break;
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case ShiftType::ROR:
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if (amount == 0) {
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eval = (value >> 1) | (carry << 31);
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carry = get_bit(value, 0);
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} else {
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eval = std::rotr(value, amount);
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carry = get_bit(value, (amount % 32 + 31) % 32);
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}
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break;
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}
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return eval;
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}
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std::ostream&
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operator<<(std::ostream& os, const ShiftType shift_type) {
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#define CASE(type) \
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case ShiftType::type: \
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os << #type; \
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break;
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switch (shift_type) {
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CASE(LSL)
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CASE(LSR)
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CASE(ASR)
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CASE(ROR)
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}
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#undef CASE
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return os;
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}
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}
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