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| author | Kartik Agaram <vc@akkartik.com> | 2019-07-09 18:02:44 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-07-09 18:05:27 -0700 |
| commit | 58d03e437a95da78f612f833a249376aa202b502 (patch) | |
| tree | 3990fb60957546376462122bff8dc0ee4fa24c5b | |
| parent | 4a96b659ff1dc16b78ba5fc607d49276b6d76c2a (diff) | |
| download | mu-58d03e437a95da78f612f833a249376aa202b502.tar.gz | |
bug: null address messing up instruction decode
Leads to a bad error message.
| -rw-r--r-- | subx/014indirect_addressing.cc | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/subx/014indirect_addressing.cc b/subx/014indirect_addressing.cc index dd00c614..3767c46d 100644 --- a/subx/014indirect_addressing.cc +++ b/subx/014indirect_addressing.cc @@ -874,7 +874,7 @@ void test_add_r32_to_mem_at_r32_plus_disp8() { } :(before "End Mod Special-cases(addr)") -case 1: // indirect + disp8 addressing +case 1: { // indirect + disp8 addressing switch (rm) { default: addr = Reg[rm].u; @@ -882,11 +882,16 @@ case 1: // indirect + disp8 addressing break; // End Mod 1 Special-cases(addr) } + int8_t displacement = static_cast<int8_t>(next()); if (addr > 0) { - addr += static_cast<int8_t>(next()); + addr += displacement; trace(Callstack_depth+1, "run") << "effective address is 0x" << HEXWORD << addr << " (after adding disp8)" << end(); } + else { + trace(Callstack_depth+1, "run") << "null address; skipping displacement" << end(); + } break; +} :(code) void test_add_r32_to_mem_at_r32_plus_negative_disp8() { |