Update README.md

Author: calmopyrin

README.md

@@ -1,51 +1,71 @@
-# reSID
+# winreSID
 
 ## MOS 6581 / 8580 SID software emulation
 
-This repository is intended to become the official source for the
-reSID MOS6581 / MOS8580 SID emulator. However for now, I recommend
-fetching reSID from [VICE](https://vice-emu.sourceforge.io/) :-)
-
-reSID is widely used in two different incarnations - reSID 0.16, which
-was released in 2004, and a reSID 1.0 prerelease, which was included
-in VICE in 2010 - 2011, and has been patched by others since
-then. Unfortunately I never got around to make an official reSID 1.0
-release.
-
-I put in a lot of work to further reverse engineer the SID chip and
-advance the state of the art of SID emulation in 2010 - 2011. This
-work was in large part based on [SID die
-shots](https://retronn.de/imports/commodore_chips.html), photographed
-and stitched by Michael Huth, and revectorized and annotated by Tommi
-Lempinen, with some further analysis by Frank Wolf. Several
-improvements were made in the digital domain, however the major
-achievement was vastly more accurate emulation in the analog domain by
-simulation of the actual analog circuits, using detailed models of
-DACs, VCRs, and op-amps. Op-amp transfer functions were obtained by
-feeding and measuring voltages directly on SID filter capacitor pins
-(with capacitors removed).
-
-A few years later, in 2016, Leandro Nini (drfiemost) started the
-thread ["Understanding the SID"](http://forum.6502.org/viewtopic.php?f=8&t=4150)
-on [forum.6502.org](http://forum.6502.org). The goal was to do a
-*complete* reverse engineering of the SID chip, based on the same die
-shots I had worked with earlier. Dieter Mueller (ttlworks) was a major
-contributor to the reverse engineering effort. Leandro Nini's and
-Dieter Mueller's work resulted in detailed
-[SID internals documentation](https://sourceforge.net/p/sidplay-residfp/wiki/SID%20internals/)
-and transistor level
-[SID schematics](https://github.com/libsidplayfp/SID_schematics).
-Leandro Nini even went as far as to create a complete transistor level
-simulation of the digital parts of the SID chip called
-[perfect6581](https://github.com/libsidplayfp/perfect6581),
-based on
-[perfect6502](https://github.com/mist64/perfect6502).
-
-In this repository I am going to pick up from where I left some ten
-years ago, cherry picking from the reverse engineering mentioned
-above, patches in VICE, and my own research, with the goal of making
-reSID even better.
-
-I also plan to use a refined reSID as the basis for an FPGA Verilog
-implementation for my take on a hardware SID replacement, the [reDIP
-SID](https://github.com/daglem/reDIP-SID).
+This repository is a fork of the venerable reSID MOS6581 / MOS8580 
+SID emulator by Dag Lem, widely used in different incarnations.
+
+## Windows library
+
+winreSID adds a simple C wrapper interface around reSID (C++) that
+makes it possible to conveniently use it in different emulators and
+applications as an optional DLL add-on.
+
+## Interface
+
+### sidCreate(unsigned int clock_type, unsigned int model, unsigned int replayFreq)
+
+Create a SID  instance with given clock_type (master clock frequency), model and 
+replay frequency.
+
+### sidDestroy()
+
+Destroy the SID instance
+
+### sidSetSampleRate(unsigned int sampleRate_)
+
+Change replay frequency to sampleRate_. Note, this is the sound replay frequency of 
+the host application.
+
+### sidSetModel(unsigned int model)
+
+Set SID model to either 6581 (=0) or 8580 (!=0).
+
+### sidReset()
+
+Resets the SID.
+### sidPause()
+
+Pause the engine
+
+### sidWriteReg(unsigned int reg, unsigned char value)
+
+Write 'value' to the SID register 'reg'.
+
+### unsigned char sidReadReg(unsigned int reg)
+
+Read SID register 'reg'. Note, some SID registers are write-only.
+The A/D ports are not implemented.
+
+### sidCalcSamples(short* buf, long count)
+
+Render 'count' samples to the sound buffer provided.
+
+### short sidCalcSample()
+
+Clock the SID engine and return one SID sound sample with the original SID frequency.
+
+### sidSetAmp(unsigned int amp)
+
+Set the amplification. Original SID output will be right shifted by this amount.
+
+### const char* sidGetLibVersion()
+
+Get the reSID library version string.
+
+## Future plans
+
+Plans include:
+- implement support for multiple instances
+- make it work as a Linux library
+- add proper library support for cycle based rendering into a buffer