Really squeezed lcd_write_data() with tricky assembler optimization. Now it does 114 fps when playing video from memory (way more than the ~75 fps needed, I need to slow down the video player), leaving headroom for audio.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4278 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn
parent
bd7c07a600
commit
c546b70e18
1 changed files with 110 additions and 6 deletions
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@ -7,7 +7,7 @@
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2002 by Alan Korr
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* Copyright (C) 2002 by Alan Korr, speedup by Jörg Hohensohn
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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@ -180,9 +180,10 @@ void lcd_write(bool command, int byte)
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Ultimately, all calls to lcd_write(false, xxx) should be substituted by
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this, it will be most efficient if the LCD buffer is tilted to have the
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X row as consecutive bytes, so we can write a whole row */
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/* FixMe: somehow the red LED is affected by this, although I don't touch
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any other bit. Therefore not used yet, except for lcd_blit() */
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void lcd_write_data(unsigned char* p_bytes, int count) __attribute__ ((section (".icode")));
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#ifdef HAVE_LCD_CHARCELLS
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/* This version works for both Player and Recorder models */
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void lcd_write_data(unsigned char* p_bytes, int count)
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{
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do
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@ -193,7 +194,8 @@ void lcd_write_data(unsigned char* p_bytes, int count)
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byte = *p_bytes++ << 24; /* fetch to MSB position */
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cli(); /* make port modifications atomic */
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cli(); /* make port modifications atomic, in case an IRQ uses PBDRL */
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/* (currently not the case, so this could be optimized away) */
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/* precalculate the values for later bit toggling, init data write */
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asm (
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@ -268,9 +270,9 @@ void lcd_write_data(unsigned char* p_bytes, int count)
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"mov.b %3,@%4\n"
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"bf 1f\n"
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"mov.b %1,@%4\n"
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"mov.b %1,@%4\n" /* set SD high, SC low still */
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"1: \n"
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"or.b %2, @(r0,gbr)\n"
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"or.b %2, @(r0,gbr)\n" /* rise SC (independent of SD level) */
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"or.b %5, @(r0,gbr)\n" /* restore port */
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:
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@ -287,3 +289,105 @@ void lcd_write_data(unsigned char* p_bytes, int count)
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} while (--count); /* tail loop is faster */
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}
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#else /* #ifdef HAVE_LCD_CHARCELLS */
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/* A further optimized version, exploits that SD is on bit 0 for recorders */
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void lcd_write_data(unsigned char* p_bytes, int count)
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{
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do
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{
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unsigned byte;
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unsigned sda1; /* precalculated SC=low,SD=1 */
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/* take inverse data, so I can use the NEGC instruction below, it is
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the only carry add/sub which does not destroy a source register */
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byte = ~(*p_bytes++ << 24); /* fetch to MSB position */
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cli(); /* make port modifications atomic, in case an IRQ uses PBDRL */
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/* (currently not the case, so this could be optimized away) */
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/* precalculate the values for later bit toggling, init data write */
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asm (
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"mov.b @%1,r0\n" /* r0 = PBDRL */
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"or %3,r0\n" /* r0 |= LCD_DS | LCD_SD DS and SD high, */
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"and %2,r0\n" /* r0 &= ~(LCD_CS | LCD_SC) CS and SC low */
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"mov.b r0,@%1\n" /* PBDRL = r0 */
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"neg r0,%0\n" /* sda1 = 0-r0 */
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: /* outputs: */
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/* %0 */ "=r"(sda1)
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: /* inputs: */
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/* %1 */ "r"(LCDR),
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/* %2 */ "I"(~(LCD_CS | LCD_SC)),
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/* %3 */ "I"(LCD_DS | LCD_SD)
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: /* trashed */
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"r0"
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);
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/* unrolled loop to serialize the byte */
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asm (
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"shll %0 \n" /* shift the MSB into carry */
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"negc %1, r0\n" /* carry to SD, SC low */
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"mov.b r0,@%3\n" /* set data to port */
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"or %2, r0\n" /* rise SC (independent of SD level) */
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"mov.b r0,@%3\n" /* set to port */
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"shll %0 \n"
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"negc %1, r0\n"
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"mov.b r0,@%3\n"
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"or %2, r0\n"
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"mov.b r0,@%3\n"
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"or %4, r0\n" /* restore port */
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"mov.b r0,@%3\n"
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: /* outputs: */
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: /* inputs: */
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/* %0 */ "r"(byte),
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/* %1 */ "r"(sda1),
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/* %2 */ "I"(LCD_SC),
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/* %3 */ "r"(LCDR),
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/* %4 */ "I"(LCD_CS|LCD_DS|LCD_SD|LCD_SC)
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: /* trashed: */
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"r0"
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);
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sti(); /* end of atomic port modifications */
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} while (--count); /* tail loop is faster */
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}
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#endif /* #ifdef HAVE_LCD_CHARCELLS */
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