diff options
Diffstat (limited to 'libpsn00b/libc')
| -rw-r--r-- | libpsn00b/libc/clz.s | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/libpsn00b/libc/clz.s b/libpsn00b/libc/clz.s new file mode 100644 index 0000000..28a28eb --- /dev/null +++ b/libpsn00b/libc/clz.s @@ -0,0 +1,43 @@ +# PSn00bSDK leading zero count intrinsics +# (C) 2022 spicyjpeg - MPL licensed +# +# libgcc provides two functions used internally by GCC to count the number of +# leading zeroes or ones in a value, _clzsi2() (32-bit) and _clzdi2() (64-bit). +# This file overrides them with faster implementations that make use of the +# GTE's LZCS/LZCR registers. + +.set noreorder + +.section .text._clzsi2 +.global _clzsi2 +.type _clzsi2, @function +_clzsi2: + mtc2 $a0, $30 + nop + nop + mfc2 $v0, $31 + + jr $ra + nop + +.section .text._clzdi2 +.global _clzdi2 +.type _clzdi2, @function +_clzdi2: + bnez $a1, .Lhas_msb + nop + + mtc2 $a0, $30 # if (!msb) return 32 + clz(lsb) + b .Lreturn + li $v1, 32 + +.Lhas_msb: + mtc2 $a1, $30 # if (msb) return 0 + clz(msb) + nop + li $v1, 0 + +.Lreturn: + mfc2 $v0, $31 + + jr $ra + addu $v0, $v1 |