Initial revision
diff --git a/src/cmd/sam/disk.c b/src/cmd/sam/disk.c
new file mode 100644
index 0000000..83b2553
--- /dev/null
+++ b/src/cmd/sam/disk.c
@@ -0,0 +1,122 @@
+#include "sam.h"
+
+static Block *blist;
+
+#if 0
+static int
+tempdisk(void)
+{
+ char buf[128];
+ int i, fd;
+
+ snprint(buf, sizeof buf, "/tmp/X%d.%.4ssam", getpid(), getuser());
+ for(i='A'; i<='Z'; i++){
+ buf[5] = i;
+ if(access(buf, AEXIST) == 0)
+ continue;
+ fd = create(buf, ORDWR|ORCLOSE|OCEXEC, 0600);
+ if(fd >= 0)
+ return fd;
+ }
+ return -1;
+}
+#else
+extern int tempdisk(void);
+#endif
+
+Disk*
+diskinit()
+{
+ Disk *d;
+
+ d = emalloc(sizeof(Disk));
+ d->fd = tempdisk();
+ if(d->fd < 0){
+ fprint(2, "sam: can't create temp file: %r\n");
+ exits("diskinit");
+ }
+ return d;
+}
+
+static
+uint
+ntosize(uint n, uint *ip)
+{
+ uint size;
+
+ if(n > Maxblock)
+ panic("internal error: ntosize");
+ size = n;
+ if(size & (Blockincr-1))
+ size += Blockincr - (size & (Blockincr-1));
+ /* last bucket holds blocks of exactly Maxblock */
+ if(ip)
+ *ip = size/Blockincr;
+ return size * sizeof(Rune);
+}
+
+Block*
+disknewblock(Disk *d, uint n)
+{
+ uint i, j, size;
+ Block *b;
+
+ size = ntosize(n, &i);
+ b = d->free[i];
+ if(b)
+ d->free[i] = b->_.next;
+ else{
+ /* allocate in chunks to reduce malloc overhead */
+ if(blist == nil){
+ blist = emalloc(100*sizeof(Block));
+ for(j=0; j<100-1; j++)
+ blist[j]._.next = &blist[j+1];
+ }
+ b = blist;
+ blist = b->_.next;
+ b->addr = d->addr;
+ d->addr += size;
+ }
+ b->_.n = n;
+ return b;
+}
+
+void
+diskrelease(Disk *d, Block *b)
+{
+ uint i;
+
+ ntosize(b->_.n, &i);
+ b->_.next = d->free[i];
+ d->free[i] = b;
+}
+
+void
+diskwrite(Disk *d, Block **bp, Rune *r, uint n)
+{
+ int size, nsize;
+ Block *b;
+
+ b = *bp;
+ size = ntosize(b->_.n, nil);
+ nsize = ntosize(n, nil);
+ if(size != nsize){
+ diskrelease(d, b);
+ b = disknewblock(d, n);
+ *bp = b;
+ }
+ if(pwrite(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
+ panic("write error to temp file");
+ b->_.n = n;
+}
+
+void
+diskread(Disk *d, Block *b, Rune *r, uint n)
+{
+ if(n > b->_.n)
+ panic("internal error: diskread");
+
+ ntosize(b->_.n, nil); /* called only for sanity check on Maxblock */
+ if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
+ panic("read error from temp file");
+}
