core: add a direct 32-bit API

Add a direct 32-bit API to some functions; initially read file only.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

4 files changed, 77 insertions, 24 deletions

diff --git a/com32/include/com32.h b/com32/include/com32.h
index aa7fb4b6..9334efb8 100644
--- a/com32/include/com32.h
+++ b/com32/include/com32.h
@@ -1,7 +1,7 @@
 /* ----------------------------------------------------------------------- *
  *
  *   Copyright 2002-2009 H. Peter Anvin - All Rights Reserved
- *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
+ *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
  *
  *   Permission is hereby granted, free of charge, to any person
  *   obtaining a copy of this software and associated documentation
@@ -92,6 +92,8 @@ typedef struct {
 #define EFLAGS_VIP		0x00100000
 #define EFLAGS_ID		0x00200000
 
+struct com32_pmapi;
+
 extern struct com32_sys_args {
     uint32_t cs_sysargs;
     char *cs_cmdline;
@@ -101,6 +103,7 @@ extern struct com32_sys_args {
     void __cdecl(*cs_farcall) (uint32_t, const com32sys_t *, com32sys_t *);
     int __cdecl(*cs_cfarcall) (uint32_t, const void *, uint32_t);
     uint32_t cs_memsize;
+    const struct com32_pmapi *cs_pm;
 } __com32;
 
 /*
diff --git a/com32/include/syslinux/pmapi.h b/com32/include/syslinux/pmapi.h
new file mode 100644
index 00000000..848a5540
--- /dev/null
+++ b/com32/include/syslinux/pmapi.h
@@ -0,0 +1,45 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2002-2009 H. Peter Anvin - All Rights Reserved
+ *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * pmapi.h
+ *
+ * Definitions for the Syslinux 4 protected-mode ABI
+ */
+
+#ifndef _SYSLINUX_PMAPI_H
+#define _SYSLINUX_PMAPI_H
+
+#include <stddef.h>
+#include <inttypes.h>
+
+struct com32_pmapi {
+    size_t (*read_file)(uint16_t *, void *, size_t);
+};
+
+#endif /* _SYSLINUX_PMAPI_H */
diff --git a/com32/lib/sys/entry.S b/com32/lib/sys/entry.S
index a3a1eaa8..629f336a 100644
--- a/com32/lib/sys/entry.S
+++ b/com32/lib/sys/entry.S
@@ -30,7 +30,7 @@
  */
 
 /* Number of arguments in our version of the entry structure */
-#define COM32_ARGS 7
+#define COM32_ARGS 8
 
 		.section ".init","ax"
 		.globl _start
diff --git a/com32/lib/sys/fileread.c b/com32/lib/sys/fileread.c
index 54ff7115..cfd49557 100644
--- a/com32/lib/sys/fileread.c
+++ b/com32/lib/sys/fileread.c
@@ -34,32 +34,23 @@
 #include <errno.h>
 #include <string.h>
 #include <com32.h>
+#include <syslinux/pmapi.h>
 #include <minmax.h>
 #include "file.h"
 
 int __file_get_block(struct file_info *fp)
 {
-    com32sys_t ireg, oreg;
+    ssize_t bytes_read;
 
-    memset(&ireg, 0, sizeof ireg);
-    ireg.eax.w[0] = 0x0007;	/* Read file */
-    ireg.ebx.w[0] = OFFS(__com32.cs_bounce);
-    ireg.es = SEG(__com32.cs_bounce);
-    ireg.esi.w[0] = fp->i.filedes;
-    ireg.ecx.w[0] = MAXBLOCK >> fp->i.blocklg2;
-
-    __intcall(0x22, &ireg, &oreg);
-
-    if (oreg.eflags.l & EFLAGS_CF) {
+    bytes_read = __com32.cs_pm->read_file(&fp->i.filedes, fp->i.buf,
+					  MAXBLOCK >> fp->i.blocklg2);
+    if (!bytes_read) {
 	errno = EIO;
 	return -1;
     }
-
-    fp->i.filedes = oreg.esi.w[0];
-    fp->i.nbytes = oreg.ecx.l;
-    fp->i.datap = fp->i.buf;
-    memcpy(fp->i.buf, __com32.cs_bounce, fp->i.nbytes);
-
+    
+    fp->i.nbytes = bytes_read;
+    fp->i.datap  = fp->i.buf;
     return 0;
 }
 
@@ -74,19 +65,33 @@ ssize_t __file_read(struct file_info * fp, void *buf, size_t count)
 	    if (fp->i.offset >= fp->i.length || !fp->i.filedes)
 		return n;	/* As good as it gets... */
 
-	    if (__file_get_block(fp))
-		return n ? n : -1;
+	    if (count > MAXBLOCK) {
+		/* Large transfer: copy directly, without buffering */
+		ncopy = __com32.cs_pm->read_file(&fp->i.filedes, bufp,
+						 count >> fp->i.blocklg2);
+		if (!ncopy) {
+		    errno = EIO;
+		    return n ? n : -1;
+		}
+
+		goto got_data;
+	    } else {
+		if (__file_get_block(fp))
+		    return n ? n : -1;
+	    }
 	}
 
 	ncopy = min(count, fp->i.nbytes);
 	memcpy(bufp, fp->i.datap, ncopy);
 
-	n += ncopy;
-	bufp += ncopy;
-	count -= ncopy;
 	fp->i.datap += ncopy;
 	fp->i.offset += ncopy;
 	fp->i.nbytes -= ncopy;
+
+    got_data:
+	n += ncopy;
+	bufp += ncopy;
+	count -= ncopy;
     }
 
     return n;