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Diffstat (limited to 'nuttx/arch/arm/src/calypso/calypso_lowputc.S')
| -rw-r--r-- | nuttx/arch/arm/src/calypso/calypso_lowputc.S | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/calypso/calypso_lowputc.S b/nuttx/arch/arm/src/calypso/calypso_lowputc.S new file mode 100644 index 000000000..951ea03d5 --- /dev/null +++ b/nuttx/arch/arm/src/calypso/calypso_lowputc.S @@ -0,0 +1,133 @@ +/************************************************************************** + * calypso/calypso_lowputc.S + * + * Copyright (C) 2011 Stefan Richter. All rights reserved. + * Author: Stefan Richter <ichgeh@l--putt.de> + * + * based on: c5471/c5471_lowputc.S + * Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + **************************************************************************/ + +/************************************************************************** + * Included Files + **************************************************************************/ + +#include <nuttx/config.h> + +#include "chip.h" +#include "up_arch.h" +#include "up_internal.h" + +/************************************************************************** + * Private Definitions + **************************************************************************/ + +/************************************************************************** + * Private Types + **************************************************************************/ + +/************************************************************************** + * Private Function Prototypes + **************************************************************************/ + +/************************************************************************** + * Global Variables + **************************************************************************/ + +/************************************************************************** + * Private Variables + **************************************************************************/ + +/************************************************************************** + * Private Functions + **************************************************************************/ + +/************************************************************************** + * Public Functions + **************************************************************************/ + +/************************************************************************** + * Name: up_lowputc + **************************************************************************/ + +/* This assembly language version has the advantage that it can does not + * require a C stack and uses only r0-r1. Hence it can be used during + * early boot phases. + */ + + .text + .global up_lowputc + .type up_lowputc, function +up_lowputc: + /* On entry, r0 holds the character to be printed */ + +#ifdef CONFIG_SERIAL_IRDA_CONSOLE + ldr r2, =UART_IRDA_BASE /* r2=IRDA UART base */ +#else + ldr r2, =UART_MODEM_BASE /* r2=Modem UART base */ +#endif + + /* Poll bit 0 of the UART_SSR register. When the bit + * is clear, the TX FIFO is no longer full + */ + +1: ldrb r1, [r2, #UART_SSR_OFFS] + tst r1, #UART_SSR_TXFULL + bne 1b + + /* Send the character by writing it into the UART_THR + * register. + */ + + strb r0, [r2, #UART_THR_OFFS] + + /* Wait for the tranmsit holding regiser (THR) to be + * emptied. This is detemined when bit 6 of the LSR + * is set. + */ + +2: ldrb r1, [r2, #UART_LSR_OFFS] + tst r1, #0x00000020 + beq 2b + + /* If the character that we just sent was a linefeed, + * then send a carriage return as well. + */ + + teq r0, #'\n' + moveq r0, #'\r' + beq 1b + + /* And return */ + + mov pc, lr + |