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Annotation of lucent/sys/src/9/bbmalloc.c, revision 1.1

1.1     ! root        1: #include       "u.h"
        !             2: #include       "../port/lib.h"
        !             3: #include       "mem.h"
        !             4: #include       "dat.h"
        !             5: #include       "fns.h"
        !             6: #include       "io.h"
        !             7: 
        !             8: /*
        !             9:  * Allocate memory for use in kernel bitblts.
        !            10:  * The allocated memory must have a flushed instruction
        !            11:  * cache, and the data cache must be flushed by bbdflush().
        !            12:  * To avoid the need for frequent cache flushes, the memory
        !            13:  * is allocated out of an arena, and the i-cache is only
        !            14:  * flushed when it has to be reused.  By returning an
        !            15:  * address in non-cached space, the need for flushing the
        !            16:  * d-cache is avoided.
        !            17:  *
        !            18:  * This code will have to be interlocked if we ever get
        !            19:  * a multiprocessor with a bitmapped display.
        !            20:  */
        !            21: 
        !            22: /* a 0->3 bitblt can take 800 longs */
        !            23: enum {
        !            24:        narena=2,       /* put interrupt time stuff in separate arena */
        !            25:        nbbarena=4096   /* number of words in an arena */
        !            26: };
        !            27: 
        !            28: static ulong   bbarena[narena][nbbarena];
        !            29: static ulong   *bbcur[narena] = {&bbarena[0][0], &bbarena[1][0]};
        !            30: static ulong   *bblast[narena] = {0, 0};
        !            31: 
        !            32: #define INTLEVEL(v)    ((v)&0x700)
        !            33: 
        !            34: extern flushvirtpage(void (*)(void));
        !            35: 
        !            36: void *
        !            37: bbmalloc(int nbytes)
        !            38: {
        !            39:        int nw, a;
        !            40:        int s;
        !            41:        ulong *ans;
        !            42: 
        !            43:        nw = nbytes/sizeof(long);
        !            44:        s = splhi();
        !            45:        a = INTLEVEL(s)? 1 : 0;
        !            46:        if(bbcur[a] + nw > &bbarena[a][nbbarena])
        !            47:                ans = bbarena[a];
        !            48:        else
        !            49:                ans = bbcur[a];
        !            50:        bbcur[a] = ans + nw;
        !            51:        splx(s);
        !            52:        bblast[a] = ans;
        !            53:        return ans;
        !            54: }
        !            55: 
        !            56: void
        !            57: bbfree(void *p, int n)
        !            58: {
        !            59:        int a, s;
        !            60: 
        !            61:        s = splhi();
        !            62:        a = INTLEVEL(s)? 1 : 0;
        !            63:        if(p == bblast[a])
        !            64:                bbcur[a] = (ulong *)(((char *)bblast[a]) + n);
        !            65:        splx(s);
        !            66: }
        !            67: 
        !            68: void
        !            69: bbdflush(void *p, int n)
        !            70: {
        !            71:        ulong pe, l;
        !            72: 
        !            73:        pe = (ulong)(((char *)p) + n + (BY2PG-1));
        !            74:        for(l = (ulong)p; l < pe; l += BY2PG)
        !            75:                flushpage(l);
        !            76: }
        !            77: 
        !            78: int
        !            79: bbonstack(void)
        !            80: {
        !            81:        if(u)
        !            82:                return 1;
        !            83:        return 0;
        !            84: }
        !            85: 
        !            86: void
        !            87: bbexec(void (*memstart)(void), int len, int onstack)
        !            88: {
        !            89:        if(onstack) {
        !            90:                flushvirtpage(memstart);
        !            91:                memstart();
        !            92:        } else {
        !            93:                bbdflush(memstart, len);
        !            94:                memstart();
        !            95:                bbfree(memstart, len);
        !            96:        }
        !            97: }

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