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Slightly improve SBCD. Not there yet though.

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This commit is contained in:
Thomas Harte 2022-05-12 07:07:21 -04:00
parent 56ce1ec6e8
commit 0efeea1294
1 changed files with 2 additions and 2 deletions

4
InstructionSets/M68k/Implementation/PerformImplementation.hpp

@ -791,9 +791,9 @@ template <
/* Perform the BCD arithmetic by evaluating the two nibbles separately. */ \
const int unadjusted_result = destination - source - (status.extend_flag_ ? 1 : 0); \
int result = (destination & 0xf) - (source & 0xf) - (status.extend_flag_ ? 1 : 0); \
if((result & 0x1f) > 0x09) result -= 0x06; \
if(result & 0xf0) result -= 0x06; \
result += (destination & 0xf0) - (source & 0xf0); \
status.extend_flag_ = status.carry_flag_ = decltype(status.carry_flag_)((result & 0x1ff) > 0x99); \
status.extend_flag_ = status.carry_flag_ = decltype(status.carry_flag_)((result & 0xff) > 0x9f); \
if(status.carry_flag_) result -= 0x60; \
\
/* Set all flags essentially as if this were normal subtraction. */ \