Update README.md

README.md

-# Efficient Reactive Intermittent Computing
+# ICLIB: a library for Reactive Intermittent Computing
 
-Library, build system and examples for ManagedState, a memory manager that uses paged memory to improve the efficiency of state retention in reactive intermittent computing.
+Library, build system and examples for three flavours of reactive intermittent 
+computing:
 
+  - QuickRecall
+  - AllocatedState
+  - ManagedState
 
-Set up for use with MSP430FR5994, but can readily be ported for similar platforms.
+**QuickRecall** is the simplest method, where all data resides in non-volatile 
+memory (FRAM). When a power failure is detected, the device saves CPU registers 
+and sleeps. Although simple, this method results in very high power consumption 
+during on-periods, because accesses to FRAM are far more expensive than those 
+to SRAM.
 
-ManagedState was presented in an academic paper,
+**AllocatedState** allocates data to SRAM to lower power consumption, and must 
+therefore load the `.data` and `.bss` sections, as well as the stack, from FRAM 
+to SRAM during  boot, and likewise save them to FRAM when power fails. 
+Although improving power consumption during the on-period, loading and saving 
+the entire allocated state can get quite expensive.
+
+**ManagedState** improves on *AllocatedState* by tracking active and modified 
+pages of memory, so that only active pages need to be loaded during boot, 
+and only modified pages need to be saved when power fails. This can 
+substantially reduce energy consumption and thereby improve performance over 
+the two other methods.
+
+
+*ManagedState* was presented in an academic paper,
 
 > "Efficient State Retention through Paged Memory Management for Reactive Transient Computing",<br />
 > Sivert T. Sliper, Domenico Balsamo, Nikos Nikoleris, William Wang, Alex S. Weddell and Geoff V. Merrett,<br />
-> IEEE Design Automation Conference (DAC 56), Las Vegas, 2019.<br />
+> IEEE Design Automation Conference (DAC 56), Las Vegas, 2019<br />
+
+available at [DOI 10.1145/33167813317812](https://doi.org/10.1145/33167813317812).
 
-The paper is available at [DOI 10.1145/33167813317812](https://doi.org/10.1145/3316781.3317812), and the supporting dataset at [DOI 10.5258/SOTON/D0835](http://dx.doi.org/10.5258/SOTON/D0835).
+## Targets
+
+Currently, *ICLIB* supports the *MSPFR5994* platform, and can readily be ported 
+to other *MSP430*-based platforms. Support for *Arm Cortex-M0* targets is under 
+development.
 
 ## Setup
 
 ### Dependencies
+
+The following dependencies are needed to build *ICLIB*:
+
   + [cmake](https://cmake.org/)
   + [MSP 430 GCC toolchain](http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPGCC/6_0_1_0/index_FDS.html) (tested with [msp430-gcc-7.3.1.24_linux64.tar.bz2](http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPGCC/6_0_1_0/exports/msp430-gcc-7.3.1.24_linux64.tar.bz2))
   + [MSP430 support files](http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPGCC/6_0_1_0/exports/msp430-gcc-support-files-1.205.zip)
@@ -23,7 +53,9 @@ The paper is available at [DOI 10.1145/33167813317812](https://doi.org/10.1145/3
     + Extract libmsp430.so from the [MSP430 Debug stack](http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPDS/3_13_0_001/index_FDS.html) to e.g. `/usr/lib`
 
 ### Paths
-Set environment variables `MSP430_GCC_ROOT`, that points to the toolchain directory, and `MSP430_INC` that points to the support file directory. This is done by e.g. adding the following two lines to your `~/.bashrc`:
+Set environment variables `MSP430_GCC_ROOT`, that points to the toolchain 
+directory, and `MSP430_INC` that points to the support file directory. This is 
+done by e.g. adding the following two lines to your `~/.bashrc`:
 
 ```bash
 export MSP430_GCC_ROOT=<path/to/MSP430 GCC folder>
@@ -31,28 +63,38 @@ export MSP430_INC=<path/to/MSP430 support files>
 ```
 
 ## Getting started
-First, build `libic.a`:
+*ICLIB* is built using CMAKE.
+To build an application make a build directory, and call CMAKE with options to 
+set the target platform. 
+
 ```bash
 cd iclib
 mkdir build
 cd build
-cmake ..
-make
-cp libic.a ..
+cmake .. -DTARGET_ARCH=msp430
 ```
 
-Then, build an example, e.g `aes`
+By default, CMAKE is set up to do a `debug` build, for benchmarking you should 
+run the `release` build:
+```bash
+cmake .. -DTARGET_ARCH=msp430 -DCMAKE_BUILD_TYPE=Release
+```
+
+Then build an executable, for example `aes` using *ManagedState*:
 
 ```bash
-cd aes128
-mkdir build
-cd build
-cmake ..
-make
+make aes-MS-msp430
 ```
 
-and program it to the development board:
+The syntax here is `<app-icmethod-target>`, where `QR` selects *QuickRecall*,
+`AS` selects *AllocatedState*, and `MS` selects *ManagedState*.
+
+Finally, on supported platforms, you can upload the executable to the 
+microcontroller using
 
 ```bash
-make upload_aes
+make upload_aes-MS-msp430
 ```
+
+Note that this uses `mspdebug`, and will only work on some setups (only tested 
+on a laptop running Ubuntu 18.04).
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