Ram Symbols

From NESTFE Wiki

Overview

RamSymbolsM is a module that allows the user to get or set any variable in a nesC application. The pc-side tool must know the sizes and memory addresses of all variables on the heap. This component is made to be used with the nescDecls system and the pytos RamSymbols module. See Development Environment Demo for more information on the RamSymbols module

The implementation of Ram Symbols can be found in tos/lib/RamSymbols

API

The RamSymbolsM module has two functions: "poke" and "peek". Poke is used to copy a value into a memory address and peek is used to read the value at a memory address. In pythos, all of a nesc application's ram symbols are imported into the environment as objects with poke and peek functions.

In pythos, the poke and peek functions can both take "arrayIndex" and "dereference" options to index into an array symbol or dereference a pointer symbol. For example:

>>> app.DrainM.sendPackets.poke(150)
.
[<class 'pytos.util.nescDecls.TosMsg'> object at 0x4caf6c0c:

        TosMsg(am=5742) PokeResponseMsg,  nodeID=1:
                 result_t value  : 1
]
>>> app.DrainM.sendPackets.peek()
.
[<class 'pytos.util.nescDecls.TosMsg'> object at 0x4cafaaac:

        TosMsg(am=5742) uint16_t,  nodeID=1:
                uint16_t value  : 151
]
>>> app.TimerM.m_period.peek(arrayIndex=0)
.
[<class 'pytos.util.nescDecls.TosMsg'> object at 0x4cafa0cc: 

        TosMsg(am=5626) int32_t,  nodeID=1:
                 int32_t value  : 32000
]
>>> app.TestRpcM.testPtr.peek(dereference=True)
.
[<class 'pytos.util.nescDecls.TosMsg'> object at 0x4cb0022c:

        TosMsg(am=5498) uint8_t,  nodeID=1:
                 uint8_t value  : 0
]

Setting Up

In order to use the API described above, the user must:

1. use the new makesystem by setting the Makerules environment variable to point to the tinyos-1.x/tools/make/Makerules file
2. add the following include directories to their makefile

CFLAGS += -I$(TOSDIR)/../tos/lib/RamSymbols

1. include the RamSymbolsM module somewhere in their application

1. invoke both the nescDecls.extra and the rpc.extra files in their make process by either declaring "nescDecls" on the command line when making the application as follows

make telosb rpc nescDecls 

or adding it to the GOALS variable in their makefile

GOALS+=rpc
GOALS+=nescDecls

For problems, the Pytos Installation Instructions setup instructions may contain more details.