From eac722cf59302e781b03f2a7add86317250eac76 Mon Sep 17 00:00:00 2001 From: Thomas Harte Date: Wed, 7 Oct 2020 18:36:17 -0400 Subject: [PATCH] Implements enough of ADC and SBC for the Dormann test definitively to fail. --- .../Implementation/65816Implementation.hpp | 39 ++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/Processors/65816/Implementation/65816Implementation.hpp b/Processors/65816/Implementation/65816Implementation.hpp index 7ed69af32..35a559e23 100644 --- a/Processors/65816/Implementation/65816Implementation.hpp +++ b/Processors/65816/Implementation/65816Implementation.hpp @@ -594,8 +594,45 @@ template void Processor::run_for(const Cycles #undef cp + case SBC: + if(flags_.decimal) { + assert(false); + break; + } + + // Implement non-decimal SBC by falling through to ADC; + // TODO: what do I need to invert to be able to fall through in both cases? And does it matter? + data_buffer_.value = ~data_buffer_.value; + [[fallthrough]]; + + case ADC: { + int result; + + if(flags_.decimal) { + result = flags_.carry; + +#define nibble(mask, limit, addition, carry) \ + result += (a_.full & mask) + (data_buffer_.value & mask); \ + if(result >= limit) result = ((result + addition) & (carry - 1)) + carry; + + nibble(0x000f, 0x000a, 0x0006, 0x00010); + nibble(0x00f0, 0x00a0, 0x0060, 0x00100); + nibble(0x0f00, 0x0a00, 0x0600, 0x01000); + nibble(0xf000, 0xa000, 0x6000, 0x10000); + +#undef nibble + + } else { + result = a_.full + data_buffer_.value + flags_.carry; + } + + flags_.overflow = (( (result ^ a_.full) & (result ^ data_buffer_.value) ) >> (1 + m_shift_))&0x40; + flags_.set_nz(result, m_shift_); + flags_.carry = (result >> (8 + m_shift_))&1; + LD(a_, result, m_masks_); + } break; + // TODO: - // ADC, SBC, // PLP, // PHP, PHD, PHK, // TRB, TSB,