diff options
| -rw-r--r-- | fns.h | 5 | ||||
| -rw-r--r-- | main.c | 4 | ||||
| -rw-r--r-- | mkfile | 1 | ||||
| -rw-r--r-- | nanosec.c | 109 |
4 files changed, 117 insertions, 2 deletions
@@ -21,3 +21,8 @@ void integrate(GameState*, double, double); Sprite *newsprite(Image*, Point, Rectangle, int, ulong); Sprite *readsprite(char*, Point, Rectangle, int, ulong); void delsprite(Sprite*); + +/* + * nanosec + */ +uvlong nanosec(void); @@ -181,7 +181,7 @@ threadmain(int argc, char *argv[]) ghoulbig = newsprite(ghoul->sheet, Pt(144,64), Rect(0,0,24,24), 5, 120); Δt = 0.01; - then = nsec(); + then = nanosec(); timeacc = 0; resetsim(); @@ -208,7 +208,7 @@ threadmain(int argc, char *argv[]) break; } - now = nsec(); + now = nanosec(); frametime = now - then; then = now; timeacc += frametime/1e9; @@ -7,6 +7,7 @@ OFILES=\ stats.$O\ physics.$O\ sprite.$O\ + nanosec.$O\ main.$O\ HFILES=\ diff --git a/nanosec.c b/nanosec.c new file mode 100644 index 0000000..6a49817 --- /dev/null +++ b/nanosec.c @@ -0,0 +1,109 @@ +#include <u.h> +#include <libc.h> +#include <tos.h> + +/* + * This code is a mixture of cpuid(1) and the nanosec() found in vmx, + * in order to force the use of nsec(2) in case we are running in a + * virtualized environment where the clock is mis-bhyve-ing. + */ + +typedef struct Res { + ulong ax, bx, cx, dx; +} Res; + +static uchar _cpuid[] = { + 0x5E, /* POP SI (PC) */ + 0x5D, /* POP BP (Res&) */ + 0x58, /* POP AX */ + 0x59, /* POP CX */ + + 0x51, /* PUSH CX */ + 0x50, /* PUSH AX */ + 0x55, /* PUSH BP */ + 0x56, /* PUSH SI */ + + 0x31, 0xDB, /* XOR BX, BX */ + 0x31, 0xD2, /* XOR DX, DX */ + + 0x0F, 0xA2, /* CPUID */ + + 0x89, 0x45, 0x00, /* MOV AX, 0(BP) */ + 0x89, 0x5d, 0x04, /* MOV BX, 4(BP) */ + 0x89, 0x4d, 0x08, /* MOV CX, 8(BP) */ + 0x89, 0x55, 0x0C, /* MOV DX, 12(BP) */ + 0xC3, /* RET */ +}; + +static Res (*cpuid)(ulong ax, ulong cx) = (Res(*)(ulong, ulong)) _cpuid; + +/* + * nsec() is wallclock and can be adjusted by timesync + * so need to use cycles() instead, but fall back to + * nsec() in case we can't + */ +uvlong +nanosec(void) +{ + static uvlong fasthz, xstart; + char buf[13], path[128]; + ulong w; + uvlong x, div; + int fd; + Res r; + + if(fasthz == ~0ULL) + return nsec() - xstart; + + /* first long in a.out header */ + snprint(path, sizeof path, "/proc/%d/text", getpid()); + fd = open(path, OREAD); + if(fd < 0) + goto Wallclock; + if(read(fd, buf, 4) != 4){ + close(fd); + goto Wallclock; + } + close(fd); + + w = ((ulong *) buf)[0]; + + switch(w){ + default: + goto Wallclock; + case 0x978a0000: /* amd64 */ + /* patch out POP BP -> POP AX */ + _cpuid[1] = 0x58; + case 0xeb010000: /* 386 */ + break; + } + segflush(_cpuid, sizeof(_cpuid)); + + r = cpuid(0x40000000, 0); + ((ulong *) buf)[0] = r.bx; + ((ulong *) buf)[1] = r.cx; + ((ulong *) buf)[2] = r.dx; + buf[12] = 0; + + if(strstr(buf, "bhyve") != nil) + goto Wallclock; + + if(fasthz == 0){ + if(_tos->cyclefreq){ + fasthz = _tos->cyclefreq; + cycles(&xstart); + } else { +Wallclock: + fasthz = ~0ULL; + xstart = nsec(); + } + return 0; + } + cycles(&x); + x -= xstart; + + /* this is ugly */ + for(div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL); + + return x / (fasthz / div); +} |