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UXTB16: Avoid undefined behaviour (shift past width)

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This commit is contained in:
Jannik Vogel 2016-05-16 21:33:05 +02:00
parent f40fabd688
commit cf92ba84ef
1 changed files with 7 additions and 5 deletions
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12
src/core/arm/dyncom/arm_dyncom_interpreter.cpp
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@ -6854,18 +6854,20 @@ unsigned InterpreterMainLoop(ARMul_State* cpu) {
uxtab_inst* const inst_cream = (uxtab_inst*)inst_base->component; uxtab_inst* const inst_cream = (uxtab_inst*)inst_base->component;
const u8 rn_idx = inst_cream->Rn; const u8 rn_idx = inst_cream->Rn;
const u32 rm_val = RM;
const u32 rotation = inst_cream->rotate * 8; const u32 rotation = inst_cream->rotate * 8;
const u32 rotated_rm = ((rm_val << (32 - rotation)) | (rm_val >> rotation)); u32 rm_val = RM;
if (rotation)
rm_val = ((rm_val << (32 - rotation)) | (rm_val >> rotation));
// UXTB16, otherwise UXTAB16 // UXTB16, otherwise UXTAB16
if (rn_idx == 15) { if (rn_idx == 15) {
RD = rotated_rm & 0x00FF00FF; RD = rm_val & 0x00FF00FF;
} else { } else {
const u32 rn_val = RN; const u32 rn_val = RN;
const u8 lo_rotated = (rotated_rm & 0xFF); const u8 lo_rotated = (rm_val & 0xFF);
const u16 lo_result = (rn_val & 0xFFFF) + (u16)lo_rotated; const u16 lo_result = (rn_val & 0xFFFF) + (u16)lo_rotated;
const u8 hi_rotated = (rotated_rm >> 16) & 0xFF; const u8 hi_rotated = (rm_val >> 16) & 0xFF;
const u16 hi_result = (rn_val >> 16) + (u16)hi_rotated; const u16 hi_result = (rn_val >> 16) + (u16)hi_rotated;
RD = ((hi_result << 16) | (lo_result & 0xFFFF)); RD = ((hi_result << 16) | (lo_result & 0xFFFF));