Java bytecode: Difference between revisions

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'''Java bytecode''' is the [[instruction set]] of the [[Java virtual machine]]. Each [[bytecode]] is composed of one, or in some cases two bytes that represent the instruction ([[opcode]]), along with zero or more bytes for passing parameters.

Of the 255 possible byte-long [[opcode]]s, {{as of|2015|lc=y}}, 198 are in use (~7778%), 54 are reserved for future use (~21%), and 3 instructions (~1%) are set aside as permanently unimplemented.<ref name="reserved_opcodes">[http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-6.html#jvms-6.2 VM Spec - Reserved Opcodes]</ref>

The Java bytecode system does not directly support floating point operations beyond 32 bits, except indirectly via bytecodes that enable use of 64-bit and 80-bit intermediate IEEE floating point operations.