122 lines
4.6 KiB
Plaintext
122 lines
4.6 KiB
Plaintext
The RX simulator offers two rx-specific configure options:
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--enable-cycle-accurate (default)
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--disable-cycle-accurate
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If enabled, the simulator will keep track of how many cycles each
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instruction takes. While not 100% accurate, it is very close,
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including modelling fetch stalls and register latency.
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--enable-cycle-stats (default)
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--disable-cycle-stats
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If enabled, specifying "-v" twice on the simulator command line causes
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the simulator to print statistics on how much time was used by each
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type of opcode, and what pairs of opcodes tend to happen most
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frequently, as well as how many times various pipeline stalls
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happened.
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The RX simulator offers many command line options:
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-v - verbose output. This prints some information about where the
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program is being loaded and its starting address, as well as
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information about how much memory was used and how many instructions
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were executed during the run. If specified twice, pipeline and cycle
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information are added to the report.
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-d - disassemble output. Each instruction executed is printed.
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-t - trace output. Causes a *lot* of printed information about what
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every instruction is doing, from math results down to register
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changes.
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--ignore-*
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--warn-*
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--error-*
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The RX simulator can detect certain types of memory corruption, and
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either ignore them, warn the user about them, or error and exit.
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Note that valid GCC code may trigger some of these, for example,
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writing a bitfield involves reading the existing value, which may
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not have been set yet. The options for * are:
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null-deref - memory access to address zero. You must modify your
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linker script to avoid putting anything at location zero, of
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course.
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unwritten-pages - attempts to read a page of memory (see below)
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before it is written. This is much faster than the next option.
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unwritten-bytes - attempts to read individual bytes before they're
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written.
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corrupt-stack - On return from a subroutine, the memory location
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where $pc was stored is checked to see if anything other than
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$pc had been written to it most recently.
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-i -w -e - these three options change the settings for all of the
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above. For example, "-i" tells the simulator to ignore all memory
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corruption.
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-E - end of options. Any remaining options (after the program name)
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are considered to be options for the simulated program, although
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such functionality is not supported.
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The RX simulator simulates a small number of peripherals, mostly in
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order to provide I/O capabilities for testing and such. The supported
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peripherals, and their limitations, are documented here.
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Memory
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Memory for the simulator is stored in a hierarchical tree, much like
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the i386's page directory and page tables. The simulator can allocate
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memory to individual pages as needed, allowing the simulated program
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to act as if it had a full 4 Gb of RAM at its disposal, without
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actually allocating more memory from the host operating system than
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the simulated program actually uses. Note that for each page of
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memory, there's a corresponding page of memory *types* (for tracking
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memory corruption). Memory is initially filled with all zeros.
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GPIO Port A
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PA.DR is configured as an output-only port (regardless of PA.DDR).
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When written to, a row of colored @ and * symbols are printed,
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reflecting a row of eight LEDs being either on or off.
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GPIO Port B
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PB.DR controls the pipeline statistics. Writing a 0 to PB.DR disables
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statistics gathering. Writing a non-0 to PB.DR resets all counters
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and enables (even if already enabled) statistics gathering. The
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simulator starts with statistics enabled, so writing to PB.DR is not
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needed if you want statistics on the entire program's run.
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SCI4
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SCI4.TDR is connected to the simulator's stdout. Any byte written to
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SCI4.TDR is written to stdout. If the simulated program writes the
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bytes 3, 3, and N in sequence, the simulator exits with an exit value
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of N.
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SCI4.SSR always returns "transmitter empty".
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TPU1.TCNT
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TPU2.TCNT
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TPU1 and TPU2 are configured as a chained 32-bit counter which counts
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machine cycles. It always runs at "ICLK speed", regardless of the
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clock control settings. Writing to either of these 16-bit registers
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zeros the counter, regardless of the value written. Reading from
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these registers returns the elapsed cycle count, with TPU1 holding the
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most significant word and TPU2 holding the least significant word.
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Note that, much like the hardware, these values may (TPU2.CNT *will*)
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change between reads, so you must read TPU1.CNT, then TPU2.CNT, and
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then TPU1.CNT again, and only trust the values if both reads of
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TPU1.CNT were the same.
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