fix lwl and lwr

068c2980 · George Hotz · f68a5470 · 068c2980
Commit 068c2980 authored Sep 30, 2021 by George Hotz
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Showing with 6 additions and 2 deletions

MIPS.sol contracts/MIPS.sol +6 -2

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--- a/contracts/MIPS.sol
+++ b/contracts/MIPS.sol
@@ -250,14 +250,18 @@ contract MIPS {
    } else if (opcode == 0x21) {  // lh
      return SE((mem >> (16-(rs&2)*8)) & 0xFFFF, 16);
    } else if (opcode == 0x22) {  // lwl
-      return mem&0xFFFF0000 | rt&0xFFFF;
+      uint32 val = mem << ((rs&3)*8);
+      uint32 mask = uint32(0xFFFFFFFF) << ((rs&3)*8);
+      return (rt & ~mask) | val;
    } else if (opcode == 0x23) { return mem;   // lw
    } else if (opcode == 0x24) {  // lbu
      return (mem >> (24-(rs&3)*8)) & 0xFF;
    } else if (opcode == 0x25) {  // lhu
      return (mem >> (16-(rs&2)*8)) & 0xFFFF;
    } else if (opcode == 0x26) {  // lwr
-      return rt&0xFFFF0000 | mem&0xFFFF;
+      uint32 val = mem >> (24-(rs&3)*8);
+      uint32 mask = uint32(0xFFFFFFFF) >> (24-(rs&3)*8);
+      return (rt & ~mask) | val;
    } else if (opcode == 0x28) { // sb
      uint32 val = (rt&0xFF) << (24-(rs&3)*8);
      uint32 mask = 0xFFFFFFFF ^ uint32(0xFF << (24-(rs&3)*8));