ref: 61ad24312b1f35fbdea73a93f1bde63181a18794
dir: /sys/src/ape/lib/ap/power/memset.s/
TEXT memset(SB),$0 #define BDNZ BC 16,0, MOVW R3, p+0(FP) /* R3 is pointer */ /* * performance: * about 100mbytes/sec (8k blocks) on a 603/105 without L2 cache * drops to 40mbytes/sec (10k blocks) and 28mbytes/sec with 32k blocks */ MOVW n+8(FP), R4 /* R4 is count */ CMP R4, $0 BLE ret MOVW c+4(FP), R5 /* R5 is char */ /* * create 16 copies of c in R5 .. R8 */ RLWNM $0, R5, $0xff, R5 RLWMI $8, R5, $0xff00, R5 RLWMI $16, R5, $0xffff0000, R5 MOVW R5, R6 MOVW R5, R7 MOVW R5, R8 /* * let STSW do the work for 16 characters or less; aligned and unaligned */ CMP R4, $16 BLE out /* * store enough bytes to align pointer */ ANDCC $7,R3, R9 BEQ l2 SUBC R9, $8, R9 MOVW R9, XER STSW R5, (R3) ADD R9, R3 SUB R9, R4 /* * store 16 at a time while there's room * STSW was used here originally, but it's `completion serialised' */ l2: SRAWCC $4, R4, R9 BLE out MOVW R9, CTR l3: MOVW R5, 0(R3) ADD $8, R3, R10 MOVW R6, 4(R3) MOVW R7, 0(R10) ADD $8, R10, R3 MOVW R8, 4(R10) BDNZ l3 RLWNMCC $0, R4, $15, R4 /* residue */ BEQ ret /* * store up to 16 bytes from R5 .. R8; aligned and unaligned */ out: MOVW R4, XER STSW R5, (R3) ret: MOVW 0(FP), R3 RETURN END