ref: ee93b99842546dc501a383e06fd0ba4af904e150
dir: /sys/src/libc/mips/lock.c/
#include <u.h> #include <libc.h> enum { Pagesize = 4096, Semperpg = Pagesize/(16*sizeof(uint)), Lockaddr = 0x60000000, POWER = 0x320, MAGNUM = 0x330, MAGNUMII = 0x340, R4K = 0x500, }; static int arch; extern int C_3ktas(int*); extern int C_4ktas(int*); extern int C_fcr0(void); static void lockinit(void) { void *v; if(arch != 0) return; /* allow multiple calls */ arch = C_fcr0(); switch(arch) { case POWER: v = (void*)Lockaddr; if(segattach(SG_CEXEC, "lock", v, Pagesize) == (void*)-1) { arch = MAGNUM; break; } memset(v, 0, Pagesize); break; case MAGNUM: case MAGNUMII: case R4K: break; default: arch = R4K; break; } } void lock(Lock *lk) { int *hwsem; int hash; retry: switch(arch) { case 0: lockinit(); goto retry; case MAGNUM: case MAGNUMII: while(C_3ktas(&lk->val)) sleep(0); return; case R4K: for(;;){ while(lk->val) ; if(C_4ktas(&lk->val) == 0) return; } break; case POWER: /* Use low order lock bits to generate hash */ hash = ((int)lk/sizeof(int)) & (Semperpg-1); hwsem = (int*)Lockaddr+hash; for(;;) { if((*hwsem & 1) == 0) { if(lk->val) *hwsem = 0; else { lk->val = 1; *hwsem = 0; return; } } while(lk->val) ; } } } int canlock(Lock *lk) { int *hwsem; int hash; retry: switch(arch) { case 0: lockinit(); goto retry; case MAGNUM: case MAGNUMII: if(C_3ktas(&lk->val)) return 0; return 1; case R4K: if(C_4ktas(&lk->val)) return 0; return 1; case POWER: /* Use low order lock bits to generate hash */ hash = ((int)lk/sizeof(int)) & (Semperpg-1); hwsem = (int*)Lockaddr+hash; if((*hwsem & 1) == 0) { if(lk->val) *hwsem = 0; else { lk->val = 1; *hwsem = 0; return 1; } } break; } return 0; } void unlock(Lock *lk) { lk->val = 0; } int _tas(int *p) { int *hwsem; int hash; retry: switch(arch) { case 0: lockinit(); goto retry; case MAGNUM: case MAGNUMII: return C_3ktas(p); case R4K: return C_4ktas(p); case POWER: /* Use low order lock bits to generate hash */ hash = ((int)p/sizeof(int)) & (Semperpg-1); hwsem = (int*)Lockaddr+hash; if((*hwsem & 1) == 0) { if(*p) *hwsem = 0; else { *p = 1; *hwsem = 0; return 0; } } break; } return 1; }