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https://github.com/libretro/virtualjaguar-libretro.git
synced 2026-11-10 03:21:27 -10:00
Joseph MattielloandClaude Opus 5.5
4841d260f7
A Doom link tic is 12 one-way single-byte hops (6 pairs, ping-pong). Two parts of the old behaviour made the tic rate depend on the vsync phase between the two devices, collapsing to 5 tics/s at bad phases even on a fast link: JLinkAwaitReply only engaged after we transmitted, so a side that only ANSWERS spun on ASISTAT with no wait, finished its frame in ~2 ms and sat in the frontend while the partner's byte arrived; every such hop then cost a whole video frame. uart.c now counts consecutive ASISTAT reads with nothing to send or receive and, past 24 in a frame, calls JLinkAwaitIdle(), which blocks like the reply wait (same frame budget and timeout) so the byte is seen the moment it arrives. A silent partner backs off exponentially (1..32 frames without idle waits); any received byte resets it. Real transports on the JagLink device only (not loopback, not the voice modem). Simulator, Doom 2P, tics/s averaged over 4 vsync phases, before -> after (emu 2 ms, 5 us poll_receive): 2 ms one-way 27.5 -> 27.5 2.5 ms 19.8 -> 26.0 3 ms 16.3 -> 20.8 4 ms 7.5 -> 19.2 Wi-Fi A (2 ms+3 jitter+2% spikes) 8.9 -> 16.0 Wi-Fi B (3 ms+8 jitter+3% spikes) 5.4 -> 9.0 3 ms with emu 6 ms 10 -> 15 Also: a once-per-5-s INFO log line while a link carries traffic (hops/s, mean hop time, wait per hop, slipped-hop share, timeouts, budget cuts, emulation cost, idle-wait hits) so the numbers can be read from the RetroArch log on iOS; netlink_sim gains --btrace/--log/--loss-pct/--rto-ms/--udp-rto-ms/ --corrupt and the clock patch gains a byte-event hook; netlink_btrace_report.py breaks hop time down by cause and analyses the Doom tic structure. Co-Authored-By: Claude Opus 5.5 <[email protected]>
65 lines
3.2 KiB
Python
65 lines
3.2 KiB
Python
#!/usr/bin/env python3
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"""Measurement-only patch for test/tools/netlink_sim.c: lets a host process
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drive jlink.c's clock and sleep (adds JLinkSimSetClock) and observe the
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byte-level link events (adds JLinkSimSetTrace). Apply to a THROWAWAY
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worktree only -- it must never be committed to src/.
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Usage: netlink_sim_clockpatch.py <worktree> (idempotent)
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JLinkSimSetTrace(fn): fn(kind, value) is called at
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1 = byte handed to the transport (JLinkWireSendByte) value = byte
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2 = byte arrived in the RX ring (JLinkRingPush) value = byte
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3 = game wrote ASIDATA (UARTWriteWord) value = byte
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4 = game read ASIDATA with RBF set (UARTReadWord) value = byte
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5 = JLinkAwaitReply entered a wait value = 0
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6 = JLinkAwaitReply returned value = 1 reply, 0 not
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netlink_sim --btrace FILE logs "inst virtual_us kind value" per event."""
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import sys
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root = sys.argv[1]
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def patch(path, edits):
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s = open(path).read()
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for old, new in edits:
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if new in s:
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continue # already applied
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if old not in s:
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sys.exit('clockpatch: anchor not found in %s: %r' % (path, old[:50]))
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s = s.replace(old, new, 1)
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open(path, 'w').write(s)
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hook = '''#include <time.h>
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#include <sys/time.h>
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#define JLINK_HAVE_WAIT 1
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static long long (*vjSimNow)(void) = 0;
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static void (*vjSimSleep)(int) = 0;
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void JLinkSimSetClock(long long (*n)(void), void (*sl)(int)) { vjSimNow = n; vjSimSleep = sl; }
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void (*vjSimTrace)(int, int) = 0;
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void JLinkSimSetTrace(void (*t)(int, int)) { vjSimTrace = t; }
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'''
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patch(root + '/src/jerry/jlink.c', [
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('#include <time.h>\n#include <sys/time.h>\n#define JLINK_HAVE_WAIT 1\n',
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hook),
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('static long long JLinkNowUsec(void)\n{\n /* CLOCK_MONOTONIC',
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'static long long JLinkNowUsec(void)\n{\n if (vjSimNow) return vjSimNow();\n /* CLOCK_MONOTONIC'),
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('static void JLinkSleepUsec(int usec)\n{\n /* nanosleep',
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'static void JLinkSleepUsec(int usec)\n{\n if (vjSimSleep) { vjSimSleep(usec); return; }\n /* nanosleep'),
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(' jlinkTxTotal++;\n if (jlinkMode == JLINK_MODE_LOOPBACK)',
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' jlinkTxTotal++;\n if (vjSimTrace) vjSimTrace(1, b);\n if (jlinkMode == JLINK_MODE_LOOPBACK)'),
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(' jlinkRing[tail] = b;\n jlinkCount++;\n',
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' jlinkRing[tail] = b;\n jlinkCount++;\n if (vjSimTrace) vjSimTrace(2, b);\n'),
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(' start = JLinkNowUsec();\n',
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' start = JLinkNowUsec();\n if (vjSimTrace) vjSimTrace(5, 0);\n'),
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(' now = JLinkNowUsec();\n jlinkWaitBudgetUsec -= (int)(now - start);',
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' now = JLinkNowUsec();\n if (vjSimTrace) vjSimTrace(6, JLinkDeliverable() > 0);\n jlinkWaitBudgetUsec -= (int)(now - start);'),
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])
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patch(root + '/src/jerry/uart.c', [
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('static uint16_t asiCtrl;',
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'extern void (*vjSimTrace)(int, int);\nstatic uint16_t asiCtrl;'),
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(' v = uartRxData;\n',
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' if (vjSimTrace && uartRxFull) vjSimTrace(4, uartRxData);\n v = uartRxData;\n'),
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(' if (!uartTxBusy)\n {\n uartTxShift = ',
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' if (vjSimTrace) vjSimTrace(3, data & 0xFF);\n if (!uartTxBusy)\n {\n uartTxShift = '),
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])
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