Generator (emulator)
From Sega Retro
Generator is an open source emulator by James Ponder designed to emulate the Sega Mega Drive/Genesis console, a popular games machine produced in the early 1990s. It is a portable program written in C and has been ported to the Amiga, Macintosh, Windows, Dreamcast and even pocket PCs such as the iPAQ and Cassiopeia. Natively, it compiles under Unix for X Windows with either tcl/tk or gtk/SDL, for svgalib and even cross-compiles to DOS with djgpp/allegro.
Generator uses it's own custom 68000 processor emulation which is and uses compilation techniques such as block-marking, flag calculation removal, operand pre-calculation, endian pre-conversion etc. There are approximately 1600 C routines generated by the first stage of compilation to cope with the 67 instruction families. These include two versions of every instruction - one that calculates flags and one that doesn't, so that unnecessary flag computation is avoided.