diff options
Diffstat (limited to 'compiler/vm.nim')
| -rw-r--r-- | compiler/vm.nim | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/compiler/vm.nim b/compiler/vm.nim index 908bbeb69..2dd6d6a9c 100644 --- a/compiler/vm.nim +++ b/compiler/vm.nim @@ -1483,6 +1483,17 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg = createStrKeepNode(regs[ra]) if regs[ra].node.strVal.isNil: regs[ra].node.strVal = newStringOfCap(1000) storeAny(regs[ra].node.strVal, typ, regs[rb].regToNode) + of opcToNarrowInt: + decodeBC(rkInt) + let mask = (1'i64 shl rc) - 1 # 0xFF + let signbit = 1'i64 shl (rc - 1) # 0x80 + let toggle = mask - signbit # 0x7F + # algorithm: -((i8 and 0xFF) xor 0x7F) + 0x7F + # mask off higher bits. + # uses two's complement to sign-extend integer. + # reajust integer into desired range. + regs[ra].intVal = -((regs[rb].intVal and mask) xor toggle) + toggle + inc pc proc execute(c: PCtx, start: int): PNode = |