64 lines
3.5 KiB
ArmAsm
64 lines
3.5 KiB
ArmAsm
/*
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* Copyright 2016 Dius Computing Pty Ltd. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of the copyright holders nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @author Johny Mattsson <jmattsson@dius.com.au>
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*/
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/* The RTOS SDK provided printf() function has explicit support for dealing
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* with formatting strings stored in flash (used via the os_printf macro).
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* For others, that's a very useful optimisation, but for us it's an unwanted
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* pessimisation as it forces a malloc for each printf. To avoid this we
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* have a minimal replacement printf() which omits the explicit flash-support
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* support, and just calls the internal SDK function print() directly.
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*/
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.section ".iram0.text"
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.type __wrap_printf,@function
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.globl __wrap_printf
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.align 4
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.literal_position
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__wrap_printf:
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addi a1, a1, -48 /* get some stack space */
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s32i a0, a1, 0 /* store a0 at the bottom */
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s32i a2, a1, 16 /* copy the formatting string and first few arguments */
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s32i a3, a1, 20 /* ...onto the stack in a way that we get a struct */
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s32i a4, a1, 24 /* ...{ uint32_t reg_args[6]; uint32_t ignore[2]; } */
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s32i a5, a1, 28 /* ...with the formatting string in the first array */
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s32i a6, a1, 32 /* ...array slot of .reg_args. */
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s32i a7, a1, 36 /* ... */
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mov a3, a2 /* print() wants the formatting string as arg 2 too */
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movi a2, 0 /* and a zero for its first arg */
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addi a4, a1, 16 /* third arg is the pointer to the argument array */
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mov a5, a4 /* as is the fourth arg */
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movi a6, 4 /* and the fifth arg is 4 (https://xkcd.com/221/ ?) */
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call0 print /* do it! */
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l32i a0, a1, 0 /* restore return address into a0 */
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addi a1, a1, 48 /* release the stack */
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ret /* all done */
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