[S] Change in coreboot[main]: acpi/acpigen: introduce and use ACPIGEN_RSVD_PKGLEN_BYTES

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/79046?usp=email )

(

7 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: acpi/acpigen: introduce and use ACPIGEN_RSVD_PKGLEN_BYTES
......................................................................

acpi/acpigen: introduce and use ACPIGEN_RSVD_PKGLEN_BYTES

Use a define instead of magic numbers.

Signed-off-by: Felix Held 
Change-Id: I2c6d17bd78a0e207f9130102b43ba78aa55ce377
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79046
Tested-by: build bot (Jenkins) 
Reviewed-by: Matt DeVillier 
Reviewed-by: Nico Huber 
---
M src/acpi/acpigen.c
1 file changed, 12 insertions(+), 14 deletions(-)

Approvals:
  Nico Huber: Looks good to me, but someone else must approve
  Matt DeVillier: Looks good to me, approved
  build bot (Jenkins): Verified

diff --git a/src/acpi/acpigen.c b/src/acpi/acpigen.c
index e5d76ba..7479dce 100644
--- a/src/acpi/acpigen.c
+++ b/src/acpi/acpigen.c
@@ -3,12 +3,9 @@
 /* How much nesting do we support? */
 #define ACPIGEN_LENSTACK_SIZE 10

-/*
- * If you need to change this, change acpigen_write_len_f and
- * acpigen_pop_len
- */
-
-#define ACPIGEN_MAXLEN 0xfffff
+/* If you need to change this, change acpigen_pop_len too */
+#define ACPIGEN_RSVD_PKGLEN_BYTES	3
+#define ACPIGEN_MAXLEN			0xfffff

#include <lib.h>
 #include <string.h>
@@ -29,11 +26,10 @@
 {
    ASSERT(ltop < (ACPIGEN_LENSTACK_SIZE - 1))
    len_stack[ltop++] = gencurrent;
-	/* Reserve 3 bytes for PkgLength. The actual byte values will be written later in the
-	   acpigen_pop_len call. */
-	acpigen_emit_byte(0);
-	acpigen_emit_byte(0);
-	acpigen_emit_byte(0);
+	/* Reserve ACPIGEN_RSVD_PKGLEN_BYTES bytes for PkgLength. The actual byte values will
+	   be written later in the corresponding acpigen_pop_len call. */
+	for (size_t i = 0; i < ACPIGEN_RSVD_PKGLEN_BYTES; i++)
+		acpigen_emit_byte(0);
 }

void acpigen_pop_len(void)
@@ -43,13 +39,14 @@
    char *p = len_stack[--ltop];
    len = gencurrent - p;
    ASSERT(len <= ACPIGEN_MAXLEN)
-	const size_t payload_len = len - 3;
+	const size_t payload_len = len - ACPIGEN_RSVD_PKGLEN_BYTES;

if (len <= 0x3f + 2) {
    	/* PkgLength of up to 0x3f can be encoded in one PkgLength byte instead of the
    	   reserved 3 bytes. Since only 1 PkgLength byte will be written, the payload
    	   data needs to be moved by 2 bytes */
-		memmove(&p[1], &p[3], payload_len);
+		memmove(&p[ACPIGEN_RSVD_PKGLEN_BYTES - 2],
+			&p[ACPIGEN_RSVD_PKGLEN_BYTES], payload_len);
    	/* Adjust the PkgLength to take into account that we only use 1 of the 3
    	   reserved bytes */
    	len -= 2;
@@ -63,7 +60,8 @@
    	/* PkgLength of up to 0xfff can be encoded in 2 PkgLength bytes instead of the
    	   reserved 3 bytes. Since only 2 PkgLength bytes will be written, the payload
    	   data needs to be moved by 1 byte */
-		memmove(&p[2], &p[3], payload_len);
+		memmove(&p[ACPIGEN_RSVD_PKGLEN_BYTES - 1],
+			&p[ACPIGEN_RSVD_PKGLEN_BYTES], payload_len);
    	/* Adjust the PkgLength to take into account that we only use 2 of the 3
    	   reserved bytes */
    	len -= 1;