diff options
Diffstat (limited to 'libpsn00b/libc/memset.s')
| -rw-r--r-- | libpsn00b/libc/memset.s | 132 |
1 files changed, 112 insertions, 20 deletions
diff --git a/libpsn00b/libc/memset.s b/libpsn00b/libc/memset.s index b3a3af3..5a1589d 100644 --- a/libpsn00b/libc/memset.s +++ b/libpsn00b/libc/memset.s @@ -1,25 +1,117 @@ -# High speed ASM memset implementation by Lameguy64 -# -# Part of PSn00bSDK +# PSn00bSDK optimized memset +# (C) 2022 spicyjpeg - MPL licensed .set noreorder -.section .text - -# Arguments: -# a0 - address to buffer -# a1 - value to set -# a2 - bytes to set +.section .text.memset .global memset -.type memset,@function +.type memset, @function memset: - move $v0, $a0 - blez $a2, .Lexit - addi $a2, -1 - sb $a1, 0($a0) - b memset - addiu $a0, 1 -.Lexit: - jr $ra - nop -
\ No newline at end of file + # If more than 16 bytes have to be written then take the "large" path, + # otherwise use the code below. + addiu $t0, $a2, -16 + bgtz $t0, .Llarge_fill + move $v0, $a0 # return_value = dest + + # Jump to one of the sb opcodes below. This is basically a cut-down Duff's + # device implementation with no looping. + la $t0, .Lsmall_duff + 0x40 # jump_addr = &small_duff[(16 - count) * 4] + sll $t1, $a2, 2 + subu $t0, $t1 + addu $a0, $a2 # dest -= 16 - count + jr $t0 + addiu $a0, -16 + +.Lsmall_duff: + sb $a1, 0x0($a0) + sb $a1, 0x1($a0) + sb $a1, 0x2($a0) + sb $a1, 0x3($a0) + sb $a1, 0x4($a0) + sb $a1, 0x5($a0) + sb $a1, 0x6($a0) + sb $a1, 0x7($a0) + sb $a1, 0x8($a0) + sb $a1, 0x9($a0) + sb $a1, 0xa($a0) + sb $a1, 0xb($a0) + sb $a1, 0xc($a0) + sb $a1, 0xd($a0) + sb $a1, 0xe($a0) + jr $ra + sb $a1, 0xf($a0) + +.Llarge_fill: + # Initialize fast filling by repeating the fill byte 4 times, so it can be + # written 32 bits at a time. + andi $a1, 0xff # ch &= 0xff + sll $t0, $a1, 8 # ch |= (ch << 8) | (ch << 16) | (ch << 24) + or $a1, $t0 + sll $t0, $a1, 16 + or $a1, $t0 + + # Fill the first 1-4 bytes (here the swr instruction does all the magic) + # and update dest and count accordingly. + swr $a1, 0($a0) + andi $t0, $a0, 3 # align = 4 - (dest % 4) + addiu $t0, -4 + addu $a2, $t0 # count -= align + subu $a0, $t0 # dest += align + + la $t1, .Llarge_duff + andi $t2, $a2, 3 # remainder = count % 4 + subu $a2, $t2 # count -= remainder + +.Llarge_fill_loop: + # If 128 bytes or more still have to be written, skip calculating the jump + # offset and execute the whole block of sw opcodes. + addiu $a2, -0x80 # count -= 0x80 + bgez $a2, .Llarge_duff + #nop + + # Jump to one of the sw opcodes below. This is the "full" Duff's device. + subu $t0, $t1, $a2 # jump_addr = &large_duff[0x80 - (count + 0x80)] + jr $t0 + addu $a0, $a2 # dest -= 0x80 - (count + 0x80) + +.Llarge_duff: + sw $a1, 0x00($a0) + sw $a1, 0x04($a0) + sw $a1, 0x08($a0) + sw $a1, 0x0c($a0) + sw $a1, 0x10($a0) + sw $a1, 0x14($a0) + sw $a1, 0x18($a0) + sw $a1, 0x1c($a0) + sw $a1, 0x20($a0) + sw $a1, 0x24($a0) + sw $a1, 0x28($a0) + sw $a1, 0x2c($a0) + sw $a1, 0x30($a0) + sw $a1, 0x34($a0) + sw $a1, 0x38($a0) + sw $a1, 0x3c($a0) + sw $a1, 0x40($a0) + sw $a1, 0x44($a0) + sw $a1, 0x48($a0) + sw $a1, 0x4c($a0) + sw $a1, 0x50($a0) + sw $a1, 0x54($a0) + sw $a1, 0x58($a0) + sw $a1, 0x5c($a0) + sw $a1, 0x60($a0) + sw $a1, 0x64($a0) + sw $a1, 0x68($a0) + sw $a1, 0x6c($a0) + sw $a1, 0x70($a0) + sw $a1, 0x74($a0) + sw $a1, 0x78($a0) + sw $a1, 0x7c($a0) + + bgtz $a2, .Llarge_fill_loop + addiu $a0, 0x80 # dest += 0x80 + + # Fill the remaining 1-4 bytes, using (again) an unaligned store. + addu $a0, $t2 # last_byte = dest + remainder - 1 + jr $ra + swl $a1, -1($a0) |