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Diffstat (limited to 'src/arch/riscv32/libgcc')
| -rw-r--r-- | src/arch/riscv32/libgcc/llshift.S | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/src/arch/riscv32/libgcc/llshift.S b/src/arch/riscv32/libgcc/llshift.S new file mode 100644 index 000000000..8ad6a6daa --- /dev/null +++ b/src/arch/riscv32/libgcc/llshift.S @@ -0,0 +1,112 @@ +/* + * Copyright (C) 2024 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + * + * You can also choose to distribute this program under the terms of + * the Unmodified Binary Distribution Licence (as given in the file + * COPYING.UBDL), provided that you have satisfied its requirements. + */ + + FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ) + +/** @file + * + * Long shifts + * + */ + + .section ".note.GNU-stack", "", @progbits + .text + +/** + * Shift left + * + * @v a1:a0 Value to shift + * @v a2 Shift amount + * @ret a1:a0 Shifted value + */ + .section ".text.__ashldi3", "ax", @progbits + .globl __ashldi3 +__ashldi3: + /* Perform shift by 32 bits, if applicable */ + li t0, 32 + sub t1, t0, a2 + bgtz t1, 1f + mv a1, a0 + mv a0, zero +1: /* Perform shift by modulo-32 bits, if applicable */ + andi a2, a2, 0x1f + beqz a2, 2f + srl t2, a0, t1 + sll a0, a0, a2 + sll a1, a1, a2 + or a1, a1, t2 +2: ret + .size __ashldi3, . - __ashldi3 + +/** + * Logical shift right + * + * @v a1:a0 Value to shift + * @v a2 Shift amount + * @ret a1:a0 Shifted value + */ + .section ".text.__lshrdi3", "ax", @progbits + .globl __lshrdi3 +__lshrdi3: + /* Perform shift by 32 bits, if applicable */ + li t0, 32 + sub t1, t0, a2 + bgtz t1, 1f + mv a0, a1 + mv a1, zero +1: /* Perform shift by modulo-32 bits, if applicable */ + andi a2, a2, 0x1f + beqz a2, 2f + sll t2, a1, t1 + srl a1, a1, a2 + srl a0, a0, a2 + or a0, a0, t2 +2: ret + .size __lshrdi3, . - __lshrdi3 + +/** + * Arithmetic shift right + * + * @v a1:a0 Value to shift + * @v a2 Shift amount + * @ret a1:a0 Shifted value + */ + .section ".text.__ashrdi3", "ax", @progbits + .globl __ashrdi3 +__ashrdi3: + /* Perform shift by 32 bits, if applicable */ + li t0, 32 + sub t1, t0, a2 + bgtz t1, 1f + mv a0, a1 + srai a1, a1, 16 + srai a1, a1, 16 +1: /* Perform shift by modulo-32 bits, if applicable */ + andi a2, a2, 0x1f + beqz a2, 2f + sll t2, a1, t1 + sra a1, a1, a2 + srl a0, a0, a2 + or a0, a0, t2 +2: ret + .size __ashrdi3, . - __ashrdi3 |