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Comprehensive technical documentation covering: - Hardware: OCS/ECS/AGA custom chip registers, Copper & Blitter deep dives - Boot sequence: cold boot through startup-sequence - Binary format: HUNK executable spec, relocation, debug info - Linking & ABI: .fd files, LVO tables, register calling conventions - Exec kernel: tasks, interrupts, memory, signals, semaphores - AmigaDOS: file I/O, FFS/OFS layout, CLI/Shell scripting - Graphics: planar bitmaps, Copper programming, HAM/EHB modes - Intuition: screens, windows, IDCMP, BOOPSI - Devices: trackdisk, SCSI, serial, timer, audio, keyboard - Libraries: utility, expansion, IFFParse, locale, ARexx - Networking: bsdsocket API, SANA-II, TCP/IP stack comparison - Toolchain: GCC, vasm/vlink, SAS/C, NDK, debugging - Reverse engineering: IDA/Ghidra setup, compiler fingerprints, case studies - CPU & MMU: 68040/060 emulation libs, PMMU, cache management - Driver development: SANA-II, Picasso96/RTG, AHI audio All files include breadcrumb navigation. No local paths or proprietary content.
151 lines
4.7 KiB
Markdown
151 lines
4.7 KiB
Markdown
[← Home](../README.md) · [CPU & MMU](README.md)
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# 68040.library and 68060.library — CPU Support Libraries
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## Overview
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The 68040 and 68060 processors **removed certain instructions** that the 68020/68030 supported in hardware. These "unimplemented" instructions cause a Line-F exception when executed. The `68040.library` and `68060.library` are **trap handler libraries** that catch these exceptions and **emulate the missing instructions in software**, providing transparent backward compatibility.
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Without these libraries, any program using the affected instructions would crash with a Line-F exception on 040/060 hardware.
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---
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## What Instructions Are Emulated?
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### 68040.library
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The 68040 removed several FPU instructions that the 68881/68882 supported:
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| Category | Missing Instructions | Description |
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|---|---|---|
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| Transcendental FPU | `FSIN`, `FCOS`, `FTAN`, `FASIN`, `FACOS`, `FATAN` | Trig functions |
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| Transcendental FPU | `FSINH`, `FCOSH`, `FTANH`, `FATANH` | Hyperbolic functions |
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| Transcendental FPU | `FLOG2`, `FLOG10`, `FLOGN`, `FLOGNP1` | Logarithms |
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| Transcendental FPU | `FETOX`, `FETOXM1`, `FTWOTOX`, `FTENTOX` | Exponentials |
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| Other FPU | `FMOD`, `FREM` | Modulo/remainder |
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| Other FPU | `FGETEXP`, `FGETMAN` | Get exponent/mantissa |
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| Other FPU | `FSGLDIV`, `FSGLMUL` | Single-precision ops |
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| Integer | `MOVEP` | Move peripheral (not on all 040 revisions) |
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### 68060.library
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The 68060 removed **everything the 040 removed** plus additional instructions:
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| Category | Additionally Missing | Description |
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|---|---|---|
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| Integer | `MOVEP` | Move peripheral (byte-strided) |
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| Integer | `CAS2` | Compare-and-swap dual |
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| Integer | `CHK2`, `CMP2` | Range check |
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| Integer | `MULU.L (64-bit)` | 64-bit unsigned multiply |
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| Integer | `MULS.L (64-bit)` | 64-bit signed multiply |
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| Integer | `DIVU.L (64-bit)` | 64-bit unsigned divide |
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| Integer | `DIVS.L (64-bit)` | 64-bit signed divide |
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| FPU | All 68040-missing FPU ops | Same as above |
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| FPU | `FMOVECR` | Move constant ROM |
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| FPU | `FDABS`, `FDSQRT`, etc. | Some double-precision ops |
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---
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## How They Work
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```
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1. Program executes FSIN (opcode $F200 xxxx)
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2. 68040/060 CPU has no microcode for this → Line-F exception (#11)
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3. CPU vectors to the Line-F exception handler
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4. 68040.library's handler decodes the opcode from the stack frame
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5. Software emulates FSIN using basic FADD/FMUL/FDIV
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6. Result is placed in the correct FPU register
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7. Handler returns → program continues as if nothing happened
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```
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---
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## Installation
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These libraries are **loaded at boot time** as resident modules. They install themselves as the Line-F exception vector handler.
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```
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; In startup-sequence or user-startup:
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LIBS:68040.library ; for 68040 systems
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; or:
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LIBS:68060.library ; for 68060 systems (replaces 68040.library)
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```
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The library is typically loaded by `SetPatch` or an explicit `C:LoadModule`:
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```
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C:LoadModule LIBS:68040.library
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; or for 68060:
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C:LoadModule LIBS:68060.library
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```
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---
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## struct (ROM Tag)
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Both libraries register as `RTF_COLDSTART` resident modules with high priority to ensure they are initialised before any user code runs:
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```c
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/* Typical RomTag for 68040.library: */
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static struct Resident romtag = {
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RTC_MATCHWORD, /* $4AFC */
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&romtag,
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&endskip,
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RTF_COLDSTART, /* flags: cold start */
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40, /* version */
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NT_LIBRARY,
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105, /* priority: very high */
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"68040.library",
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"68040.library 40.1 (1.1.93)\r\n",
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initRoutine
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};
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```
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---
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## Detection
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```c
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/* Check which CPU is present: */
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if (SysBase->AttnFlags & AFF_68040) /* 68040 */
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if (SysBase->AttnFlags & AFF_68060) /* 68060 */
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/* AttnFlags bits: */
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#define AFB_68010 0
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#define AFB_68020 1
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#define AFB_68030 2
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#define AFB_68040 3
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#define AFB_68060 7 /* added by 68060.library */
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#define AFB_68881 4 /* FPU present */
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#define AFB_68882 5
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#define AFB_FPU40 6 /* 040 internal FPU */
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```
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---
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## Performance Impact
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Software emulation of transcendental FPU instructions is **10–100x slower** than the 68881/68882 hardware implementation. Performance-critical code should:
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- Use lookup tables for trig functions
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- Use polynomial approximations (Chebyshev, CORDIC)
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- Avoid `FSIN`/`FCOS` in tight loops
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---
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## Common Sources
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| Library | Source |
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| 68040.library 37.4 | Commodore (OS 3.0 distribution) |
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| 68040.library 40.1 | Commodore (OS 3.1 distribution) |
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| 68060.library 40.1 | Phase5 (original 68060 accelerators) |
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| 68060.library 46.x | Motorola reference implementation |
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---
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## References
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- Motorola: *MC68040 User's Manual* — unimplemented instruction list
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- Motorola: *MC68060 User's Manual* — unimplemented instruction list
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- NDK39: `exec/execbase.h` — `AttnFlags`
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- Phase5: 68060.library source (public domain)
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