diff options
| -rw-r--r-- | engines/sci/engine/vm.cpp | 24 | ||||
| -rw-r--r-- | engines/sci/engine/vm_types.cpp | 23 | ||||
| -rw-r--r-- | engines/sci/engine/vm_types.h | 1 |
3 files changed, 27 insertions, 21 deletions
diff --git a/engines/sci/engine/vm.cpp b/engines/sci/engine/vm.cpp index a6677ee633..69d046da7d 100644 --- a/engines/sci/engine/vm.cpp +++ b/engines/sci/engine/vm.cpp @@ -961,28 +961,10 @@ void run_vm(EngineState *s) { s->r_acc = POP32() / s->r_acc; break; - case op_mod: { // 0x05 (05) - if (getSciVersion() <= SCI_VERSION_0_LATE) { - uint16 modulo = s->r_acc.requireUint16(); - uint16 value = POP32().requireUint16(); - uint16 result = (modulo != 0 ? value % modulo : 0); - s->r_acc = make_reg(0, result); - } else { - // In Iceman (and perhaps from SCI0 0.000.685 onwards in general), - // handling for negative numbers was added. Since Iceman doesn't - // seem to have issues with the older code, we exclude it for now - // for simplicity's sake and use the new code for SCI01 and newer - // games. Fixes the battlecruiser mini game in SQ5 (room 850), - // bug #3035755 - int16 modulo = ABS(s->r_acc.requireSint16()); - int16 value = POP32().requireSint16(); - int16 result = (modulo != 0 ? value % modulo : 0); - if (result < 0) - result += modulo; - s->r_acc = make_reg(0, result); - } + case op_mod: // 0x05 (05) + // we check for division by 0 inside the custom reg_t modulo operator + s->r_acc = POP32() % s->r_acc; break; - } case op_shr: // 0x06 (06) // Shift right logical diff --git a/engines/sci/engine/vm_types.cpp b/engines/sci/engine/vm_types.cpp index a165bf7cc3..c5b106d212 100644 --- a/engines/sci/engine/vm_types.cpp +++ b/engines/sci/engine/vm_types.cpp @@ -113,6 +113,29 @@ reg_t reg_t::operator/(const reg_t right) const { return lookForWorkaround(right); } +reg_t reg_t::operator%(const reg_t right) const { + if (isNumber() && right.isNumber()) { + // Support for negative numbers was added in Iceman, and perhaps in + // SCI0 0.000.685 and later. Theoretically, this wasn't really used + // in SCI0, so if we do find such a case, error out on purpose here, + // so that we address it properly, as the result is probably + // unpredictable. Such a case would indicate either a script bug, or + // a modulo on an unsigned integer larger than 32767. In any case, + // such a case should be investigated, instead of being silently + // accepted. + if (getSciVersion() <= SCI_VERSION_0_LATE && (toSint16() < 0 || right.toSint16() < 0)) + error("Modulo of a negative number has been requested for SCI0. " + "Please report this error to the ScummVM team"); + int16 value = toSint16(); + int16 modulo = ABS(right.toSint16()); + int16 result = (modulo != 0 ? value % modulo : 0); + if (result < 0) + result += modulo; + return make_reg(0, result); + } else + return lookForWorkaround(right); +} + reg_t reg_t::operator>>(const reg_t right) const { if (isNumber() && right.isNumber()) return make_reg(0, toUint16() >> right.toUint16()); diff --git a/engines/sci/engine/vm_types.h b/engines/sci/engine/vm_types.h index 0187906670..ac23bbe7dc 100644 --- a/engines/sci/engine/vm_types.h +++ b/engines/sci/engine/vm_types.h @@ -108,6 +108,7 @@ struct reg_t { reg_t operator-(const reg_t right) const; reg_t operator*(const reg_t right) const; reg_t operator/(const reg_t right) const; + reg_t operator%(const reg_t right) const; reg_t operator>>(const reg_t right) const; reg_t operator<<(const reg_t right) const; |