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From: Arvind Sankar <nivedita@alum.mit.edu>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 08/14] efi/gop: Use helper macros for find_bits
Date: Thu, 19 Mar 2020 15:28:49 -0400
Message-ID: <20200319192855.29876-9-nivedita@alum.mit.edu> (raw)
In-Reply-To: <20200319192855.29876-1-nivedita@alum.mit.edu>

Use the __ffs/__fls macros to calculate the position and size of the
mask.

Correct type of mask to u32 instead of unsigned long.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
 drivers/firmware/efi/libstub/gop.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 7b0baf9a912f..8bf424f35759 100644
--- a/drivers/firmware/efi/libstub/gop.c
+++ b/drivers/firmware/efi/libstub/gop.c
@@ -5,6 +5,7 @@
  *
  * ----------------------------------------------------------------------- */
 
+#include <linux/bitops.h>
 #include <linux/efi.h>
 #include <linux/screen_info.h>
 #include <asm/efi.h>
@@ -12,27 +13,16 @@
 
 #include "efistub.h"
 
-static void find_bits(unsigned long mask, u8 *pos, u8 *size)
+static void find_bits(u32 mask, u8 *pos, u8 *size)
 {
-	u8 first, len;
-
-	first = 0;
-	len = 0;
-
-	if (mask) {
-		while (!(mask & 0x1)) {
-			mask = mask >> 1;
-			first++;
-		}
-
-		while (mask & 0x1) {
-			mask = mask >> 1;
-			len++;
-		}
+	if (!mask) {
+		*pos = *size = 0;
+		return;
 	}
 
-	*pos = first;
-	*size = len;
+	/* UEFI spec guarantees that the set bits are contiguous */
+	*pos  = __ffs(mask);
+	*size = __fls(mask) - *pos + 1;
 }
 
 static void
-- 
2.24.1


  parent reply index

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-19 19:28 [PATCH 00/14] efi/gop: Refactoring + mode-setting feature Arvind Sankar
2020-03-19 19:28 ` [PATCH 01/14] efi/gop: Remove redundant current_fb_base Arvind Sankar
2020-03-19 19:28 ` [PATCH 02/14] efi/gop: Move check for framebuffer before con_out Arvind Sankar
2020-03-19 19:28 ` [PATCH 03/14] efi/gop: Get mode information outside the loop Arvind Sankar
2020-03-19 19:28 ` [PATCH 04/14] efi/gop: Factor out locating the gop into a function Arvind Sankar
2020-03-19 19:28 ` [PATCH 05/14] efi/gop: Slightly re-arrange logic of find_gop Arvind Sankar
2020-03-19 19:28 ` [PATCH 06/14] efi/gop: Move variable declarations into loop block Arvind Sankar
2020-03-19 19:28 ` [PATCH 07/14] efi/gop: Use helper macros for populating lfb_base Arvind Sankar
2020-03-19 19:28 ` Arvind Sankar [this message]
2020-03-19 19:28 ` [PATCH 09/14] efi/gop: Remove unreachable code from setup_pixel_info Arvind Sankar
2020-03-19 19:28 ` [PATCH 10/14] efi/gop: Add prototypes for query_mode and set_mode Arvind Sankar
2020-03-19 19:28 ` [PATCH 11/14] efi/gop: Allow specifying mode number on command line Arvind Sankar
2020-03-19 22:53   ` kbuild test robot
2020-03-20  1:09   ` kbuild test robot
2020-03-20 14:36   ` Dan Carpenter
2020-03-20 17:51     ` Arvind Sankar
2020-03-19 19:28 ` [PATCH 12/14] efi/gop: Allow specifying mode by <xres>x<yres> Arvind Sankar
2020-03-19 19:28 ` [PATCH 13/14] efi/gop: Allow specifying depth as well as resolution Arvind Sankar
2020-03-19 19:28 ` [PATCH 14/14] efi/gop: Allow automatically choosing the best mode Arvind Sankar
2020-03-19 20:02 ` [PATCH 00/14] efi/gop: Refactoring + mode-setting feature Ard Biesheuvel
2020-03-20  2:00 ` [PATCH v2 " Arvind Sankar
2020-03-25 16:41   ` Ard Biesheuvel
2020-03-25 22:10     ` Arvind Sankar
2020-03-25 23:36       ` Ard Biesheuvel
2020-03-26 10:41         ` Ard Biesheuvel
2020-03-28 16:06           ` efi/gop: skip cur_mode in choose_mode_auto Arvind Sankar
2020-03-28 16:06             ` [PATCH v3] efi/gop: Allow automatically choosing the best mode Arvind Sankar
2020-03-29  7:47             ` efi/gop: skip cur_mode in choose_mode_auto Ard Biesheuvel
2020-03-26 23:56         ` [PATCH v2 00/14] efi/gop: Refactoring + mode-setting feature Arvind Sankar
2020-03-28 15:43           ` Ard Biesheuvel
2020-03-25 16:50   ` Hans de Goede
2020-03-25 22:13     ` Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 01/14] efi/gop: Remove redundant current_fb_base Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 02/14] efi/gop: Move check for framebuffer before con_out Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 03/14] efi/gop: Get mode information outside the loop Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 04/14] efi/gop: Factor out locating the gop into a function Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 05/14] efi/gop: Slightly re-arrange logic of find_gop Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 06/14] efi/gop: Move variable declarations into loop block Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 07/14] efi/gop: Use helper macros for populating lfb_base Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 08/14] efi/gop: Use helper macros for find_bits Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 09/14] efi/gop: Remove unreachable code from setup_pixel_info Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 10/14] efi/gop: Add prototypes for query_mode and set_mode Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 11/14] efi/gop: Allow specifying mode number on command line Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 12/14] efi/gop: Allow specifying mode by <xres>x<yres> Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 13/14] efi/gop: Allow specifying depth as well as resolution Arvind Sankar
2020-03-20  2:00 ` [PATCH v2 14/14] efi/gop: Allow automatically choosing the best mode Arvind Sankar

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