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cmd: redefine getbuf as concatenating slices

simpler, more robust

--- a/cmd.c

+++ b/cmd.c

@@ -4,8 +4,6 @@

 #include "dat.h"

 #include "fns.h"

-/* stupidest implementation with the least amount of state to keep track of */

-

 Dot dot;

 usize totalsz;

 static Chunk norris = {.left = &norris, .right = &norris};

@@ -120,7 +118,6 @@

 		dot.to.pos += Δ;

 }

-/* stupidest possible approach for now: minimal bookkeeping */

 Chunk *

 p2c(usize p, usize *off)

 {

@@ -294,51 +291,23 @@

 	return c->buf + off;

 }

-uchar *

-getbuf(Dot d, usize n, uchar *scratch, usize *boff)

+vlong

+getbuf(Dot d, usize n, uchar *buf, usize bufsz)

 {

-	uchar *bp, *p;

-	usize Δbuf, Δloop, m, off, Δ;

-	Chunk *c;

+	uchar *p, *b;

+	usize sz;

-	if(d.pos >= totalsz){

-		*boff = 0;

-		return nil;

+	assert(d.pos < totalsz);

+	assert(n <= bufsz);

+	b = buf;

+	while(n > 0){

+		if((p = getslice(&d, n, &sz)) == nil || sz < Sampsz)

+			return -1;

+		memcpy(b, p, sz);

+		b += sz;

+		n -= sz;

 	}

-	c = p2c(d.pos, &off);

-	p = c->buf + off;

-	m = n;

-	bp = scratch;

-	while(m > 0){

-		Δloop = d.to.pos - d.pos;

-		Δbuf = c->bufsz - off;

-		if(m < Δloop && m < Δbuf){

-			Δ = m;

-			memcpy(bp, p, Δ);

-			d.pos += Δ;

-		}else if(Δloop <= Δbuf){

-			Δ = Δloop;

-			memcpy(bp, p, Δ);

-			d.pos = d.from.pos;

-			c = p2c(d.from.pos, nil);

-			off = 0;

-			p = c->buf;

-		}else{

-			if(c == &norris)

-				c = c->right;

-			Δ = Δbuf;

-			memcpy(bp, p, Δ);

-			d.pos += Δ;

-			c = c->right;

-			off = 0; 

-			p = c->buf;

-		}

-		bp += Δ;

-		m -= Δ;

-	}

-	if(boff != nil)

-		*boff = n;

-	return scratch;

+	return b - buf;

 }

 void

@@ -542,6 +511,8 @@

 static int

 writebuf(int fd)

 {

+	static uchar *buf;

+	static usize bufsz;

 	int nio;

 	usize n, m, c, k;

 	uchar *p;

@@ -551,14 +522,17 @@

 	d.to.pos = dot.to.pos;

 	if((nio = iounit(fd)) == 0)

 		nio = 8192;

-	nio = MIN(nio, sizeof plentyofroom);

+	if(bufsz < nio){

+		buf = erealloc(buf, nio, bufsz);

+		bufsz = nio;

+	}

 	for(m=d.to.pos-d.from.pos, c=0; m>0;){

 		k = nio < m ? nio : m;

-		if((p = getbuf(d, k, plentyofroom, &k)) == nil){

-			fprint(2, "writebuf: couldn\'t get a buffer: %r\n");

+		if(getbuf(d, k, buf, bufsz) < 0){

+			fprint(2, "writebuf: couldn\'t snarf: %r\n");

 			return -1;

 		}

-		if((n = write(fd, p, k)) != k){

+		if((n = write(fd, buf, k)) != k){

 			fprint(2, "writebuf: short write not %zd: %r\n", k);

 			return -1;

 		}

@@ -566,7 +540,7 @@

 		d.pos += n;

 		c += n;

 	}

-	write(fd, plentyofroom, 0);	/* close pipe */

+	write(fd, buf, 0);	/* close pipe */

 	return 0;

 }

--- a/fns.h

+++ b/fns.h

@@ -15,7 +15,7 @@

 void	setrange(usize, usize);

 int	setpos(usize);

 uchar*	getslice(Dot*, usize, usize*);

-uchar*	getbuf(Dot, usize, uchar*, usize*);

+vlong	getbuf(Dot, usize, uchar*, usize);

 int	loadin(int);

 void*	emalloc(usize);

 void*	erealloc(void*, usize, usize);

--- a/pplay.c

+++ b/pplay.c

@@ -22,19 +22,18 @@

 athread(void *)

 {

 	int nerr;

-	uchar *p;

-	usize n;

+	vlong n;

 	nerr = 0;

 	for(;;){

 		if(afd < 0 || nerr > 10)

 			return;

-		if((p = getbuf(dot, Outsz, sbuf, &n)) == nil){

+		if((n = getbuf(dot, Outsz, sbuf, sizeof sbuf)) < 0){

 			fprint(2, "athread: %r\n");

 			nerr++;

 			continue;

 		}

-		if(write(afd, p, n) != n){

+		if(write(afd, sbuf, n) != n){

 			fprint(2, "athread write: %r (nerr %d)\n", nerr);

 			break;

 		}