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-rw-r--r--src/core/arm/interpreter/armemu.cpp25
1 files changed, 24 insertions, 1 deletions
diff --git a/src/core/arm/interpreter/armemu.cpp b/src/core/arm/interpreter/armemu.cpp
index b9ac8b9ad..399ee0886 100644
--- a/src/core/arm/interpreter/armemu.cpp
+++ b/src/core/arm/interpreter/armemu.cpp
@@ -6326,7 +6326,30 @@ L_stm_s_takeabort:
printf ("Unhandled v6 insn: smmla/smmls/smmul\n");
break;
case 0x78:
- printf ("Unhandled v6 insn: usad/usada8\n");
+ if (BITS(20, 24) == 0x18)
+ {
+ const u8 rm_idx = BITS(8, 11);
+ const u8 rn_idx = BITS(0, 3);
+ const u8 rd_idx = BITS(16, 19);
+
+ const u32 rm_val = state->Reg[rm_idx];
+ const u32 rn_val = state->Reg[rn_idx];
+
+ const u8 diff1 = (u8)::abs((rn_val & 0xFF) - (rm_val & 0xFF));
+ const u8 diff2 = (u8)::abs(((rn_val >> 8) & 0xFF) - ((rm_val >> 8) & 0xFF));
+ const u8 diff3 = (u8)::abs(((rn_val >> 16) & 0xFF) - ((rm_val >> 16) & 0xFF));
+ const u8 diff4 = (u8)::abs(((rn_val >> 24) & 0xFF) - ((rm_val >> 24) & 0xFF));
+
+ u32 finalDif = (diff1 + diff2 + diff3 + diff4);
+
+ // Op is USADA8 if true.
+ const u8 ra_idx = BITS(12, 15);
+ if (ra_idx != 15)
+ finalDif += state->Reg[ra_idx];
+
+ state->Reg[rd_idx] = finalDif;
+ return 1;
+ }
break;
case 0x7a:
printf ("Unhandled v6 insn: usbfx\n");