# Compiler 80cc > 80cc experimental/alternate C compiler in z88dk. Use when -compiler=80cc or working under src/80cc. - Skill: `z88dk/compiler-80cc` (Agent Skill) - Install (CLI): `npx skillmds@latest add z88dk/compiler-80cc` - Raw SKILL.md: https://api.skillmd.com/api/skills/z88dk/compiler-80cc/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: z88dk (https://skillmd.com/u/z88dk) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/z88dk/compiler-80cc --- # Compiler — 80cc Binary: `z88dk-80cc`. Source: `src/80cc/`. Rules file: `lib/80cc_rules.1`. ## Agent facts 1. Select via `zcc -compiler=80cc` when the target allows it. 2. `-compiler=multi` also runs 80cc. It always compiles `80cc-sp`. It compiles `80cc-fp` when 80cc treats the CPU as having IX. Spec: `src/zcc-multi/zcc-compiler-multi.md`. 3. Do not assume sccz80 or sdcc runtime helpers match 80cc output. 4. Prefer reading `src/80cc` notes for current status before large work. 5. Rebuild: `make -C src/80cc PREFIX=$(pwd)` from the z88dk root, then `make -C src/80cc PREFIX=$(pwd) install`. 6. The `--version` / `-h` banner comes from `src/config.h` `Z88DK_VERSION`. That string can be stale after a rebuild. Prove a hunk with `strings bin/z88dk-80cc`, not the banner. 7. kc160 `mul de,hl` is **integer** 16×16. `_Float16` / accum16 stay on `l_f16_mul` / `l_fix16_*`. Do not emit IR_MUL for those (math16 80cc kc160 suite: `1.5*1.5` and `0*Inf`). ## Frame pointer (Z80 benches) | Flag | Meaning | |------|---------| | `-fframe-pointer` | IX is the frame pointer (`ix+d` locals). Use on **Z80** 80cc TIMER / PRINTF recipes, including `--math-mbf32`. | | (default) | Omit the frame pointer. Locals via `sp`. IX is a spare index register. | 8085 has no IX. Do not pass `-fframe-pointer` on `-clib=8085`. Integer benches (sieve, fannkuch) are usually smaller and faster with `-fframe-pointer`. math32 TIMER is usually **slower and larger**: extra time is in 80cc C glue (`ix+d`, byte `add/adc a,(ix+d)`, spills around `l_f32_*`). math32 library cycle counts stay the same. Prove with ticks hotspots rolled up to the C function (`advance`, `selectRandom`), not to `CLIB_*` const symbols. Recipe comment used in `z88dk-classic/readme.txt`: ```text # Z80 80cc: -fframe-pointer (IX). ``` ## TIMER / correctness - Classic: `+test -compiler=80cc -DSTATIC -DTIMER -D__Z88DK` (no `PRINTF` for published ticks). - Some 80cc sources need `__asm__("TIMER_START:");` (same as vanilla SDCC). - Dhrystone: `-DNOSTRUCTASSIGN`. TIMER is **not** published (Run_Index loop exits in ~800 cycles). - 80cc+8085 sorting: qsort does not link. Do not invent 8085 80cc sort rows. - Mandelbrot image: `z88dk-ticks … -output verify.bin` then `z88dk-appmake +extract -b verify.bin -s 0xc000 -l 480 -o image.bin`. Compare to `z88dk-classic/image-golden.bin`. One edge pixel can differ (float). Many last-bytes-of-row (≈15) means missing variable-count byte `<<` (PR #3066). ## PR #3066 (mandelbrot leftover pack) Not on `master` until merged. Branch `80cc_mandelbrot_pr`. | Hunk | Role | |------|------| | `gen_shl` width-1 + `op->src[1] >= 0` | Count in B, `add a,a` loop. Else `imm` is 0 and the leftover byte is `<< 0`. | | `gen_ld_mem` `ld a,(bc)` / `(de)` | Gate on `bc_has` / `de_has` (live), not `vreg_in_pr_bc` / `de`. | | `compound_assign.sh` `ca_char_shl_var` | Expect `00c0`. A lone `zcc +test` of that snippet can print `c0` even without the hunk. Trust the suite or the full mandelbrot image. | Use `emit_sp` for the BC push/pop. Three-way merge onto current master is clean. Do not cherry-pick only the last commit. Prove the binary has the fix: `strings bin/z88dk-80cc | rg bshl_loop`. ## Condensed wiki # Tool — z88dk-80cc Alternate small-C style compiler. Select with **`-compiler=80cc`** on the zcc line. ## Capability summary | | | |--|--| | Role | A/B codegen vs sccz80; some float benchmarks | | Not | Full day-to-day replacement for sccz80/zsdcc | | CPUs | See help (`-m8080`, `-m8085`, `-mz80`, …) | ## Help (live) ```text 80cc - z80 family Crosscompiler Version: 25141-6b30e0885e-20260716 (C) 1980-2026 Cain, Van Zandt, Hendrix, Yorston, z88dk Usage: z88dk-80cc [flags] [file] -v -verbose Be verbose -h -help Show this help page -o -output Set the output filename CPU Targetting: -m8080 Generate output for the i8080 -m8085 Generate output for the i8085 -mez80_z80 Generate output for the ez80 in z80 mode -mz80 Generate output for the z80 -mz80n Generate output for the z80n -mz180 Generate output for the z180 -mr2ka Generate output for the Rabbit 2000A -mr3k Generate output for the Rabbit 3000 -mr4k Generate output for the Rabbit 4000 -mr6k Generate output for the Rabbit 4000 -mgbz80 Generate output for the Gameboy CPU -mkc160 Generate output for the KC160 Code generation options -unsigned Make all types unsigned --disable-builtins Disable builtin functions -params-offset = Base offset for the function parameters (default: 2) -math-z88 (deprecated) Make FP constants match z88 -banked-style=regular Use regular banked calling style -banked-style=ti Use ticalc banked calling style -fp-exponent-bias = FP exponent bias (default: 128) -fp-mantissa-size = FP mantissa size (default: 5 bytes) -fp-mode=z80 Use 48 bit doubles -fp-mode=ieee Use 32 bit IEEE doubles -fp-mode=mbf32 Use 32 bit Microsoft Binary format -fp-mode=mbf40 Use 40 bit Microsoft binary format -fp-mode=mbf64 Use 64 bit Microsoft binary format -fp-mode=z88 Use 40 bit z88 doubles -fp-mode=am9511 Use 32 bit AM9511 doubles -standard-escape-chars Use standard mappings for \r and \n (inert — escapes are always standard) -set-r2l-by-default Use r->l calling convention by default --constseg = Set the const section name --codeseg = Set the code section name --bssseg = Set the bss section name --dataseg = Set the data section name --initseg = Set the initialisation section name -gcline Generate C_L … (more in wiki page) ## Related - `tool-zcc`, `tool-copt`, `methodology-measure`, `methodology-sdcc-vanilla` (not 80cc) - Multi selector: `src/zcc-multi/zcc-compiler-multi.md`