From 9c2c89b7e1a93b52b53c567116b0d24bc4cb6ce7 Mon Sep 17 00:00:00 2001 From: Lioncash Date: Mon, 12 Jan 2015 00:01:46 -0500 Subject: dyncom: Add a helper function for addition with a carry --- src/core/arm/interpreter/armsupp.cpp | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'src/core/arm/interpreter/armsupp.cpp') diff --git a/src/core/arm/interpreter/armsupp.cpp b/src/core/arm/interpreter/armsupp.cpp index 68ac2a0c..e2626eef 100644 --- a/src/core/arm/interpreter/armsupp.cpp +++ b/src/core/arm/interpreter/armsupp.cpp @@ -418,6 +418,22 @@ ARMul_NegZero (ARMul_State * state, ARMword result) } } +// Add with carry, indicates if a carry-out or signed overflow occurred. +u32 AddWithCarry(u32 left, u32 right, u32 carry_in, bool* carry_out_occurred, bool* overflow_occurred) +{ + u64 unsigned_sum = (u64)left + (u64)right + (u64)carry_in; + s64 signed_sum = (s64)(s32)left + (s64)(s32)right + (s64)carry_in; + u64 result = (unsigned_sum & 0xFFFFFFFF); + + if (carry_out_occurred) + *carry_out_occurred = (result != unsigned_sum); + + if (overflow_occurred) + *overflow_occurred = ((s64)(s32)result != signed_sum); + + return (u32)result; +} + // Compute whether an addition of A and B, giving RESULT, overflowed. bool AddOverflow(ARMword a, ARMword b, ARMword result) { -- cgit v1.2.3