[S] Change in coreboot[master]: [SKETCH] acpigen: Pipe data in acpigen_dsm_uuid_enum_functions()

[Nico Huber (Code Review)]

Nico Huber has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/76092?usp=email )

Change subject: [SKETCH] acpigen: Pipe data in acpigen_dsm_uuid_enum_functions()
......................................................................

[SKETCH] acpigen: Pipe data in acpigen_dsm_uuid_enum_functions()

Change-Id: Iad15af08c39d0ddb477216bc3e93bc799899bb0e
Signed-off-by: Nico Huber 
---
M src/acpi/acpigen.c
1 file changed, 20 insertions(+), 10 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/92/76092/1

diff --git a/src/acpi/acpigen.c b/src/acpi/acpigen.c
index fb92b89..051bc67 100644
--- a/src/acpi/acpigen.c
+++ b/src/acpi/acpigen.c
@@ -1670,13 +1670,18 @@
    acpigen_emit_byte(dst_op);
 }

+static void acpigen_start_byte_buffer(size_t size)
+{
+	acpigen_emit_byte(BUFFER_OP);
+	acpigen_write_len_f();
+	acpigen_write_integer(size);
+}
+
 void acpigen_write_byte_buffer(uint8_t *arr, size_t size)
 {
    size_t i;

-	acpigen_emit_byte(BUFFER_OP);
-	acpigen_write_len_f();
-	acpigen_write_integer(size);
+	acpigen_start_byte_buffer(size);

for (i = 0; i < size; i++)
    	acpigen_emit_byte(arr[i]);
@@ -1767,28 +1772,33 @@
 static void acpigen_dsm_uuid_enum_functions(const struct dsm_uuid *id)
 {
    const size_t bytes = DIV_ROUND_UP(id->count, BITS_PER_BYTE);
-	uint8_t *buffer = alloca(bytes);
-	bool set = false;
    size_t cb_idx = 0;
+	bool set = false;

-	memset(buffer, 0, bytes);
+	acpigen_emit_byte(RETURN_OP);
+	acpigen_start_byte_buffer(bytes);
+
+	/* Keep byte0 location for later patching. */
+	uint8_t *const byte0 = (uint8_t *)acpigen_get_current();

for (size_t i = 0; i < bytes; i++) {
+		uint8_t byte = 0;
    	for (size_t j = 0; j < BITS_PER_BYTE; j++) {
    		if (cb_idx >= id->count)
    			break;

if (id->callbacks[cb_idx++]) {
    			set = true;
-				buffer[i] |= BIT(j);
+				byte |= BIT(j);
    		}
    	}
+		acpigen_emit_byte(byte);
    }

-	if (set)
-		buffer[0] |= BIT(0);
+	/* Patch bit0 */
+	*byte0 |= set;

-	acpigen_write_return_byte_buffer(buffer, bytes);
+	acpigen_pop_len();
 }

static void acpigen_write_dsm_uuid(struct dsm_uuid *id)