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// license:BSD-3-Clause
// copyright-holders:hap
// SM530 shared opcode handlers
#include "emu.h"
#include "sm530.h"
// internal helpers
void sm530_device::do_branch(u8 pu, u8 pl)
{
// set new PC(Pu/Pl)
m_pc = ((pu << 6) | (pl & 0x3f)) & m_prgmask;
}
// instruction set
// RAM address instructions
void sm530_device::op_lb()
{
// LB x: load BM/BL with 4-bit immediate value (partial)
m_bl = (m_op << 2 & 8) | (m_op & 1) | 6;
m_bm = m_op >> 2 & 3;
}
void sm530_device::op_incb()
{
// INCB: increment BL, but overflow on 3rd bit!
sm510_base_device::op_incb();
m_skip = (m_bl == 8);
}
// ROM address instructions
void sm530_device::op_tl()
{
// TL xy: long jump
do_branch((m_op << 2) | (m_param >> 6 & 3), m_param & 0x3f);
}
void sm530_device::op_trs()
{
// TRS x: indirect subroutine call, jump vectors are on page 14
m_icount--;
push_stack();
u8 jump = m_program->read_byte((14 << 6) | (m_op & 0x3f));
do_branch(jump >> 5 & 7, jump & 0x1f);
}
// Arithmetic instructions
void sm530_device::op_adx()
{
// ADX x: add immediate value to ACC, skip next on carry
m_acc += (m_op & 0xf);
m_skip = bool(m_acc & 0x10);
m_acc &= 0xf;
}
// I/O instructions
void sm530_device::op_atbp()
{
// ATBP: output ACC to BP
m_bp = m_acc;
}
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