some questions about the internal

[espruino-discuss3]

Posted at 2015-06-21 by Long

Here are two questions puzzled me a lot.
1.Could someone give me some examples for the members of the structure of JsExecInfo(execInfo) and JsLex would be when typing codes like

"1 + 1" or "digitalWrite(LED1,1)"

in the terminal. I already have seen the notes for the members of these two structures, but I do not understand well. It can be better for me if someone can give me the general idea for the course of parsing js codes in jsparse.c .

2.I find that when I type codes in the terminal, the reason why these codes can be showed in the terminal is the function jshUSARTKick() in the file "jshardware.c", but I do not know how the function jshUSARTKick() is called. I have not found the the corresponding codes for this function calling. Could someone help me ?

[gfwilliams]

Posted at 2015-06-22 by @gfwilliams

1. I'm afraid you won't see anything useful in execInfo when parsing that code. The relevant datastructures tend to be stored as local variables. For example for 1+1, __jspeBinaryExpression will get called, and will execute this with 1 in the a variable and 1 in the b variable.

2. I'd highly recommend compiling Espruino under Linux with make clean;DEBUG=1 make. That'll make an executable that'll run on Linux itself, that you can then debug with gdb ./espruino. You can then breakpoint things and find out where they're called from.

But the sequence of calls looks like:

• jsiConsolePrint in jsinteractive.c (prints text)
• jsiConsolePrintChar in jsinteractive.c (print a char)
• jshTransmit in jsdevices.c (Add character to the output buffer)
• jshUSARTKick (Makes sure USART starts transmitting - further characters are pulled from the output buffer in an interrupt handler)