shithub: mp3dec

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if seeking is impossible, buffer some first for minimp3 to be able to seek

--- a/mp3dec.c

+++ b/mp3dec.c

@@ -4,15 +4,24 @@

 #define MINIMP3_IMPLEMENTATION

 #include "minimp3_ex.h"

-static int noseek;

+static int noseek, startsz;

+static uvlong curpos;

 static Biobuf in;

 static uchar inb[MINIMP3_BUF_SIZE];

+static uchar start[2*MINIMP3_BUF_SIZE];

 static size_t

 readcb(void *buf, size_t size, void *)

 {

 	int n;

-	n = Bread(&in, buf, size);

+	if(noseek && curpos < startsz){

+		n = startsz - curpos;

+		n = size < n ? size : n;

+		memmove(buf, start+curpos, n);

+		curpos += n;

+	}else{

+		n = Bread(&in, buf, size);

+	}

 	return n > 0 ? n : 0;

 }

@@ -19,8 +28,10 @@

 static int

 seekcb(uint64_t position, void *)

 {

-	if(!noseek)

-		Bseek(&in, position, 0);

+	if(noseek && curpos <= startsz)

+		curpos = position;

+	else

+		curpos = Bseek(&in, position, 0);

 	return 0;

 }

@@ -60,6 +71,8 @@

 	noseek = Bseek(&in, 0, 2) < 0;

 	if(!noseek)

 		Bseek(&in, 0, 0);

+	else

+		startsz = Bread(&in, start, sizeof(start));

 	if(mp3dec_ex_open_cb(&dec, &io, MP3D_SEEK_TO_SAMPLE|MP3D_DO_NOT_SCAN) != 0)

 		sysfatal("mp3dec_ex_open_cb");

 	if(seekto != 0.0)