From 059c65a27af538cba40aa43d2eeb3a544661a9b8 Mon Sep 17 00:00:00 2001 From: Lioncash Date: Sun, 28 Dec 2014 06:07:24 -0500 Subject: [PATCH] armemu: Fix underflows in USAD8/USADA8 Initially reported by xdec. --- src/core/arm/interpreter/armemu.cpp | 8 ++++---- src/core/arm/interpreter/armsupp.cpp | 9 +++++++++ src/core/arm/skyeye_common/armemu.h | 1 + 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/src/core/arm/interpreter/armemu.cpp b/src/core/arm/interpreter/armemu.cpp index 9b680c1e2a..404012b2a8 100644 --- a/src/core/arm/interpreter/armemu.cpp +++ b/src/core/arm/interpreter/armemu.cpp @@ -6643,10 +6643,10 @@ L_stm_s_takeabort: const u32 rm_val = state->Reg[rm_idx]; const u32 rn_val = state->Reg[rn_idx]; - const u8 diff1 = (u8)std::labs((rn_val & 0xFF) - (rm_val & 0xFF)); - const u8 diff2 = (u8)std::labs(((rn_val >> 8) & 0xFF) - ((rm_val >> 8) & 0xFF)); - const u8 diff3 = (u8)std::labs(((rn_val >> 16) & 0xFF) - ((rm_val >> 16) & 0xFF)); - const u8 diff4 = (u8)std::labs(((rn_val >> 24) & 0xFF) - ((rm_val >> 24) & 0xFF)); + const u8 diff1 = ARMul_UnsignedAbsoluteDifference(rn_val & 0xFF, rm_val & 0xFF); + const u8 diff2 = ARMul_UnsignedAbsoluteDifference((rn_val >> 8) & 0xFF, (rm_val >> 8) & 0xFF); + const u8 diff3 = ARMul_UnsignedAbsoluteDifference((rn_val >> 16) & 0xFF, (rm_val >> 16) & 0xFF); + const u8 diff4 = ARMul_UnsignedAbsoluteDifference((rn_val >> 24) & 0xFF, (rm_val >> 24) & 0xFF); u32 finalDif = (diff1 + diff2 + diff3 + diff4); diff --git a/src/core/arm/interpreter/armsupp.cpp b/src/core/arm/interpreter/armsupp.cpp index 6774f8a74a..61639d1560 100644 --- a/src/core/arm/interpreter/armsupp.cpp +++ b/src/core/arm/interpreter/armsupp.cpp @@ -392,6 +392,15 @@ ARMul_NthReg (ARMword instr, unsigned number) return (bit - 1); } +/* Unsigned sum of absolute difference */ +u8 ARMul_UnsignedAbsoluteDifference(u8 left, u8 right) +{ + if (left > right) + return left - right; + + return right - left; +} + /* Assigns the N and Z flags depending on the value of result. */ void diff --git a/src/core/arm/skyeye_common/armemu.h b/src/core/arm/skyeye_common/armemu.h index 3ea14b5a31..04c5d2e1ae 100644 --- a/src/core/arm/skyeye_common/armemu.h +++ b/src/core/arm/skyeye_common/armemu.h @@ -600,6 +600,7 @@ extern ARMword ARMul_SwitchMode (ARMul_State *, ARMword, ARMword); extern ARMword ARMul_Align (ARMul_State *, ARMword, ARMword); extern ARMword ARMul_SwitchMode (ARMul_State *, ARMword, ARMword); extern void ARMul_MSRCpsr (ARMul_State *, ARMword, ARMword); +extern u8 ARMul_UnsignedAbsoluteDifference(u8, u8); extern void ARMul_SubOverflow (ARMul_State *, ARMword, ARMword, ARMword); extern void ARMul_AddOverflow (ARMul_State *, ARMword, ARMword, ARMword); extern void ARMul_AddOverflowQ(ARMul_State*, ARMword, ARMword);