X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dos_sbtest;a=blobdiff_plain;f=src%2Fau_sb.c;fp=src%2Fau_sb.c;h=8ff4ea1d430ae8b257b3461e36a1d181a865b091;hp=ab12b9e405f5d26aeaa9ab485949ee40c2fcf036;hb=85710b37e4082a5b8e6d35c16311cb024298e24f;hpb=6d4de53a835a8258ba05c83a2af38f27a0e92d21

diff --git a/src/au_sb.c b/src/au_sb.c
index ab12b9e..8ff4ea1 100644
--- a/src/au_sb.c
+++ b/src/au_sb.c
@@ -169,18 +169,23 @@ void *sb_buffer(int *size)
 
 void sb_start(int rate, int nchan)
 {
+	int seg, pmsel;
 	uint32_t addr;
 	int size;
 	_go32_dpmi_seginfo intr;
 
-	/* for now just use the are after boot2. it's only used by the second stage
-	 * loader and the VBE init code, none of which should overlap with audio playback.
-	 * It's not necessary to use low memory. We can use up to the first 16mb for this,
-	 * so if this becomes an issue, I'll make a DMA buffer allocator over 1mb.
-	 * start the buffer from the next 64k boundary.
-	 */
-	addr = ((uint32_t)low_mem_buffer + 0xffff) & 0xffff0000;
-	buffer = (void*)addr;
+	if(!buffer) {
+		/* allocate a 64k-aligned 64k buffer in low memory */
+		if((seg = __dpmi_allocate_dos_memory(65536 * 2 / 16, &pmsel)) <= 0) {
+			fprintf(stderr, "sb_start: failed to allocate DMA buffer\n");
+			return;
+		}
+
+		addr = ((uint32_t)(seg << 4) + 0xffff) & 0xffff0000;
+		buffer = (void*)addr;
+	} else {
+		addr = (uint32_t)buffer;
+	}
 
 	xfer_mode = CMD_MODE_SIGNED;
 	if(nchan > 1) {