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LCD flip (upside down) and a high-performance blit function

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4143 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn 2003-12-12 22:11:08 +00:00
parent e3be10107d
commit 56271b571a
3 changed files with 158 additions and 7 deletions
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113
firmware/drivers/lcd.c
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@ -173,3 +173,116 @@ void lcd_write(bool command, int byte)
: /* %0 */ "I"(LCD_CS|LCD_DS|LCD_SD|LCD_SC),
/* %1 */ "z"(LCDR));
}
/* A high performance function to write data to the display,
one or multiple bytes.
Ultimately, all calls to lcd_write(false, xxx) should be substituted by
this, it will be most efficient if the LCD buffer is tilted to have the
X row as consecutive bytes, so we can write a whole row */
/* FixMe: somehow the red LED is affected by this, although I don't touch
any other bit. Therefore not used yet, except for lcd_blit() */
void lcd_write_data(unsigned char* p_bytes, int count) __attribute__ ((section (".icode")));
void lcd_write_data(unsigned char* p_bytes, int count)
{
do
{
unsigned byte;
unsigned sda1; /* precalculated SC=low,SD=1 */
unsigned clk0sda0; /* precalculated SC and SD low */
cli(); /* make port modifications atomic */
/* precalculate the values for later bit toggling, init data write */
asm (
"mov.b @%2,%0\n" /* sda1 = PBDRL */
"or %4,%0\n" /* sda1 |= LCD_DS | LCD_SD DS and SD high, */
"and %3,%0\n" /* sda1 &= ~(LCD_CS | LCD_SC) CS and SC low */
"mov %0,%1\n" /* sda1 -> clk0sda0 */
"and %5,%1\n" /* clk0sda0 &= ~LCD_SD both low */
"mov.b %1,@%2\n" /* PBDRL = clk0sda0 */
: // outputs
/* %0 */ "=r"(sda1),
/* %1 */ "=r"(clk0sda0)
: // inputs
/* %2 */ "r"(LCDR),
/* %3 */ "r"(~(LCD_CS | LCD_SC)),
/* %4 */ "r"(LCD_DS | LCD_SD),
/* %5 */ "r"(~LCD_SD)
);
byte = *p_bytes++ << 24; /* fetch to MSB position */
/* unrolled loop to serialize the byte */
asm (
"mov %4,r0\n" /* we need &PBDRL in r0 for "or.b x,@(r0,gbr)" */
"shll %0\n" /* shift the MSB into carry */
"bf 1f\n"
"mov.b %1,@%4\n" /* if it was a "1": set SD high, SC low still */
"1: \n"
"or.b %2, @(r0,gbr)\n" /* rise SC (independent of SD level) */
"shll %0\n" /* shift for next round, now for longer hold time */
"mov.b %3,@%4\n" /* SC and SD low again */
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"shll %0\n"
"mov.b %3,@%4\n"
"bf 1f\n"
"mov.b %1,@%4\n"
"1: \n"
"or.b %2, @(r0,gbr)\n"
"or.b %5, @(r0,gbr)\n" /* restore port */
:
: /* %0 */ "r"(byte),
/* %1 */ "r"(sda1),
/* %2 */ "I"(LCD_SC),
/* %3 */ "r"(clk0sda0),
/* %4 */ "r"(LCDR),
/* %5 */ "I"(LCD_CS|LCD_DS|LCD_SD|LCD_SC)
);
sti();
} while (--count); /* tail loop is faster */
}