/*
 * MIPS DSPr2 optimizations for libjpeg-turbo
 *
 * Copyright (C) 2013, MIPS Technologies, Inc., California.
 * Copyright (C) 2018, Matthieu Darbois.
 * All Rights Reserved.
 * Authors:  Teodora Novkovic (teodora.novkovic@imgtec.com)
 *           Darko Laus       (darko.laus@imgtec.com)
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */

#define zero $0
#define AT   $1
#define v0   $2
#define v1   $3
#define a0   $4
#define a1   $5
#define a2   $6
#define a3   $7
#define t0   $8
#define t1   $9
#define t2   $10
#define t3   $11
#define t4   $12
#define t5   $13
#define t6   $14
#define t7   $15
#define s0   $16
#define s1   $17
#define s2   $18
#define s3   $19
#define s4   $20
#define s5   $21
#define s6   $22
#define s7   $23
#define t8   $24
#define t9   $25
#define k0   $26
#define k1   $27
#define gp   $28
#define sp   $29
#define fp   $30
#define s8   $30
#define ra   $31

#define f0   $f0
#define f1   $f1
#define f2   $f2
#define f3   $f3
#define f4   $f4
#define f5   $f5
#define f6   $f6
#define f7   $f7
#define f8   $f8
#define f9   $f9
#define f10  $f10
#define f11  $f11
#define f12  $f12
#define f13  $f13
#define f14  $f14
#define f15  $f15
#define f16  $f16
#define f17  $f17
#define f18  $f18
#define f19  $f19
#define f20  $f20
#define f21  $f21
#define f22  $f22
#define f23  $f23
#define f24  $f24
#define f25  $f25
#define f26  $f26
#define f27  $f27
#define f28  $f28
#define f29  $f29
#define f30  $f30
#define f31  $f31

#ifdef __ELF__
#define HIDDEN_SYMBOL(symbol) .hidden symbol;
#else
#define HIDDEN_SYMBOL(symbol)
#endif

/*
 * LEAF_MIPS32R2 - declare leaf routine for MIPS32r2
 */
#define LEAF_MIPS32R2(symbol)                           \
                .globl  symbol;                         \
                HIDDEN_SYMBOL(symbol)                   \
                .align  2;                              \
                .type   symbol, @function;              \
                .ent    symbol, 0;                      \
symbol:         .frame  sp, 0, ra;                      \
                .set    push;                           \
                .set    arch=mips32r2;                  \
                .set    noreorder;                      \
                .set    noat;

/*
 * LEAF_MIPS_DSPR2 - declare leaf routine for MIPS DSPr2
 */
#define LEAF_MIPS_DSPR2(symbol)                         \
LEAF_MIPS32R2(symbol)                                   \
                .set    dspr2;

/*
 * END - mark end of function
 */
#define END(function)                                   \
                .set    pop;                            \
                .end    function;                       \
                .size   function,.-function

/*
 * Checks if stack offset is big enough for storing/restoring regs_num
 * number of register to/from stack. Stack offset must be greater than
 * or equal to the number of bytes needed for storing registers (regs_num*4).
 * Since MIPS ABI allows usage of first 16 bytes of stack frame (this is
 * preserved for input arguments of the functions, already stored in a0-a3),
 * stack size can be further optimized by utilizing this space.
 */
.macro CHECK_STACK_OFFSET regs_num, stack_offset
.if \stack_offset < \regs_num * 4 - 16
.error "Stack offset too small."
.endif
.endm

/*
 * Saves set of registers on stack. Maximum number of registers that
 * can be saved on stack is limitted to 14 (a0-a3, v0-v1 and s0-s7).
 * Stack offset is number of bytes that are added to stack pointer (sp)
 * before registers are pushed in order to provide enough space on stack
 * (offset must be multiple of 4, and must be big enough, as described by
 * CHECK_STACK_OFFSET macro). This macro is intended to be used in
 * combination with RESTORE_REGS_FROM_STACK macro. Example:
 *  SAVE_REGS_ON_STACK      4, v0, v1, s0, s1
 *  RESTORE_REGS_FROM_STACK 4, v0, v1, s0, s1
 */
.macro SAVE_REGS_ON_STACK stack_offset = 0, r1, \
                          r2  = 0, r3  = 0, r4  = 0, \
                          r5  = 0, r6  = 0, r7  = 0, \
                          r8  = 0, r9  = 0, r10 = 0, \
                          r11 = 0, r12 = 0, r13 = 0, \
                          r14 = 0
    .if (\stack_offset < 0) || (\stack_offset - (\stack_offset / 4) * 4)
    .error "Stack offset must be pozitive and multiple of 4."
    .endif
    .if \stack_offset != 0
    addiu           sp, sp, -\stack_offset
    .endif
    sw              \r1, 0(sp)
    .if \r2 != 0
    sw              \r2, 4(sp)
    .endif
    .if \r3 != 0
    sw              \r3, 8(sp)
    .endif
    .if \r4 != 0
    sw              \r4, 12(sp)
    .endif
    .if \r5 != 0
    CHECK_STACK_OFFSET 5, \stack_offset
    sw              \r5, 16(sp)
    .endif
    .if \r6 != 0
    CHECK_STACK_OFFSET 6, \stack_offset
    sw              \r6, 20(sp)
    .endif
    .if \r7 != 0
    CHECK_STACK_OFFSET 7, \stack_offset
    sw              \r7, 24(sp)
    .endif
    .if \r8 != 0
    CHECK_STACK_OFFSET 8, \stack_offset
    sw              \r8, 28(sp)
    .endif
    .if \r9 != 0
    CHECK_STACK_OFFSET 9, \stack_offset
    sw              \r9, 32(sp)
    .endif
    .if \r10 != 0
    CHECK_STACK_OFFSET 10, \stack_offset
    sw              \r10, 36(sp)
    .endif
    .if \r11 != 0
    CHECK_STACK_OFFSET 11, \stack_offset
    sw              \r11, 40(sp)
    .endif
    .if \r12 != 0
    CHECK_STACK_OFFSET 12, \stack_offset
    sw              \r12, 44(sp)
    .endif
    .if \r13 != 0
    CHECK_STACK_OFFSET 13, \stack_offset
    sw              \r13, 48(sp)
    .endif
    .if \r14 != 0
    CHECK_STACK_OFFSET 14, \stack_offset
    sw              \r14, 52(sp)
    .endif
.endm

/*
 * Restores set of registers from stack. Maximum number of registers that
 * can be restored from stack is limitted to 14 (a0-a3, v0-v1 and s0-s7).
 * Stack offset is number of bytes that are added to stack pointer (sp)
 * after registers are restored (offset must be multiple of 4, and must
 * be big enough, as described by CHECK_STACK_OFFSET macro). This macro is
 * intended to be used in combination with RESTORE_REGS_FROM_STACK macro.
 * Example:
 *  SAVE_REGS_ON_STACK      4, v0, v1, s0, s1
 *  RESTORE_REGS_FROM_STACK 4, v0, v1, s0, s1
 */
.macro RESTORE_REGS_FROM_STACK stack_offset = 0, r1, \
                               r2  = 0, r3  = 0, r4  = 0, \
                               r5  = 0, r6  = 0, r7  = 0, \
                               r8  = 0, r9  = 0, r10 = 0, \
                               r11 = 0, r12 = 0, r13 = 0, \
                               r14 = 0
    .if (\stack_offset < 0) || (\stack_offset - (\stack_offset/4)*4)
    .error "Stack offset must be pozitive and multiple of 4."
    .endif
    lw              \r1, 0(sp)
    .if \r2 != 0
    lw              \r2, 4(sp)
    .endif
    .if \r3 != 0
    lw              \r3, 8(sp)
    .endif
    .if \r4 != 0
    lw              \r4, 12(sp)
    .endif
    .if \r5 != 0
    CHECK_STACK_OFFSET 5, \stack_offset
    lw              \r5, 16(sp)
    .endif
    .if \r6 != 0
    CHECK_STACK_OFFSET 6, \stack_offset
    lw              \r6, 20(sp)
    .endif
    .if \r7 != 0
    CHECK_STACK_OFFSET 7, \stack_offset
    lw              \r7, 24(sp)
    .endif
    .if \r8 != 0
    CHECK_STACK_OFFSET 8, \stack_offset
    lw              \r8, 28(sp)
    .endif
    .if \r9 != 0
    CHECK_STACK_OFFSET 9, \stack_offset
    lw              \r9, 32(sp)
    .endif
    .if \r10 != 0
    CHECK_STACK_OFFSET 10, \stack_offset
    lw              \r10, 36(sp)
    .endif
    .if \r11 != 0
    CHECK_STACK_OFFSET 11, \stack_offset
    lw              \r11, 40(sp)
    .endif
    .if \r12 != 0
    CHECK_STACK_OFFSET 12, \stack_offset
    lw              \r12, 44(sp)
    .endif
    .if \r13 != 0
    CHECK_STACK_OFFSET 13, \stack_offset
    lw              \r13, 48(sp)
    .endif
    .if \r14 != 0
    CHECK_STACK_OFFSET 14, \stack_offset
    lw              \r14, 52(sp)
    .endif
    .if \stack_offset != 0
    addiu           sp, sp, \stack_offset
    .endif
.endm