Version history¶

Z80 v0.2-pre¶

Released on 2025-05-02

This is an important update that addresses a number of issues and also includes new features. Please note that the changes introduced in this release break the binary compatibility with the previous version.

Changes:

Changed the license from GPL to LGPL (by popular request).
Moved the public header from <emulation/CPU/Z80.h> to <Z80.h>.
Removed the Xcode project.
Switched the build system from Premake to CMake.
Switched to Zeta v0.1.
Added pkg-config support.
Added the following files to the project: .vimrc, CITATION.cff and THANKS.
Added detailed documentation.
Added Pascal binding, courtesy of Zoran Vučenović.
Added test-Z80, a tool that runs various Z80-specific tests for CP/M and ZX Spectrum.
Added step-test-Z80, a tool for unit tests in JSON format.
Renamed the macros CPU_Z80_DEPENDENCIES_H and CPU_Z80_STATIC to Z80_EXTERNAL_HEADER and Z80_STATIC, respectively.
Added public macros for checking the library version, working with flags, accessing the 16-bit registers and other purposes.
Added the ability to end the emulation loop immediately, and the z80_break() function.
Added the z80_execute() function for running a simplified emulation without RESET and interrupts.
Added the z80_in_cycle() and z80_out_cycle() functions for obtaining the clock cycle at which the I/O M-cycle begins, relative to the start of the instruction.
Added the z80_refresh_address() function for getting the refresh address of the current M1 cycle.
Renamed the z80_reset function to z80_instant_reset().
Added optional emulation of the special RESET, and the z80_special_reset() function.
Added the Z80::fetch_opcode and Z80::fetch callbacks for performing, respectively, opcode fetch operations and memory read operations on instruction data.
Added the Z80::nop callback for performing disregarded opcode fetch operations during internal NOP M-cycles.
Added emulation of the NMI acknowledge M-cycle through the new Z80::nmia callback.
Added emulation of the INT acknowledge M-cycle through the new Z80::inta callback, which replaces Z80::int_data.
Added optional full emulation of the interrupt mode 0, along with the new Z80::int_fetch callback for performing bus read operations on instruction data. If not enabled at compile-time, the old simplified emulation is built, which supports only the most typical instructions.
Added four callbacks for notifying the execution of important instructions: Z80::ld_i_a, Z80::ld_r_a, Z80::reti and Z80::retn.
Added hooking functionality through the ld h,h instruction and the new Z80::hook callback.
Added the Z80::illegal callback for delegating the emulation of illegal instructions.
Added emulation options that can be configured at runtime.
Removed Z80::state. Replaced with individual members for the registers, the interrupt enable flip-flops and the interrupt mode.
Removed the superfluous EI flag. The previous opcode is checked instead, which is faster and makes the Z80 object smaller.
Removed all module-related stuff.
Added emulation of the additional flag changes performed during the extra 5 clock cycles of the following instructions: ldir, lddr, cpir, cpdr, inir, indr, otir and otdr.
Added emulation of the interrupt acceptance deferral that occurs during the reti and retn instructions.
Added MEMPTR emulation. The bit N,(hl) instruction now produces a correct value of F.
Added optional emulation of Q. If enabled at compile-time, the ccf and scf instructions will produce a correct value of F.
Added emulation of the out (c),255 instruction (Zilog Z80 CMOS).
Added optional emulation of the bug affecting the ld a,{i|r} instructions (Zilog Z80 NMOS). If enabled at compile-time and configured at runtime, the P/V flag will be reset if an INT is accepted during the execution of these instructions.
Added an optional implementation of the parity calculation for the P/V flag that performs the actual computation instead of using a table of precomputed values.
Added an optional implementation of the daa instruction that uses a table of precomputed values.
Increased granularity. The emulator can now stop directly after fetching a prefix DDh or FDh if it runs out of clock cycles. This also works during the INT response in mode 0.
Reimplemented the HALT state. The emulation should now be fully accurate. HALTskip optimization is also supported.
Fixed a bug in the sll instruction.
Fixed a bug in the INX and OUTX macros affecting the S and N flags.
Fixed a bug in the OUTX macro affecting the MSByte of the port number.
Fixed the clock cycles of the dec XY and in (c) instructions.
Fixed the read_16 function so that the order of the memory read operations is not determined by the order in which the compiler evaluates expressions.
Fixed the order in which the memory write operations are performed when the SP register is involved. This affects the NMI response, the INT response in modes 1 and 2, and the following instructions: ex (sp),{hl|XY}, push TT, push XY, call WORD, call Z,WORD and rst N.
Fixed the handling of illegal instructions to avoid stack overflows in long sequences of DDh/FDh prefixes.
Fixed several implicit conversions to avoid warnings about loss of sign and precision.
Fixed some bitwise operations to avoid undefined behavior and arithmetic right shifts on signed integers.
Fixed violations of the C standard in several identifiers.
Renamed the 8-bit register lists: X/Y to J/K; J/K and P/Q to O/P.
Replaced all P/V overflow computation functions with a single, faster macro.
Replaced all register resolution functions with macros.
Replaced all ld {J,K|O,P} instructions that have the same destination and source register with NOPs. In addition, the “illegal” forms of the following instructions are now executed without using the illegal instruction handler: ld O,P, ld O,BYTE, U [a,]P and V O.
Optimizations in flag computation and condition evaluation.
New source code comments and improvements to existing ones.
Improved code aesthetics.
Other improvements, optimizations and minor changes.

Z80 v0.1¶

Released on 2018-11-10

Initial public release.