1 /* 2 * String's compareTo. 3 * 4 * Requires a0/a1 to have been previously checked for null. Will 5 * return negative if this's string is < comp, 0 if they are the 6 * same and positive if >. 7 * 8 * IMPORTANT NOTE: 9 * 10 * This code relies on hard-coded offsets for string objects, and must be 11 * kept in sync with definitions in UtfString.h. See asm-constants.h 12 * 13 * On entry: 14 * a0: this object pointer 15 * a1: comp object pointer 16 * 17 */ 18 19 subu v0, a0, a1 # Same? 20 bnez v0, 1f 21 RETURN 22 1: 23 lw t0, STRING_FIELDOFF_OFFSET(a0) 24 lw t1, STRING_FIELDOFF_OFFSET(a1) 25 lw t2, STRING_FIELDOFF_COUNT(a0) 26 lw a2, STRING_FIELDOFF_COUNT(a1) 27 lw a0, STRING_FIELDOFF_VALUE(a0) 28 lw a1, STRING_FIELDOFF_VALUE(a1) 29 30 /* 31 * At this point, we have this/comp: 32 * offset: t0/t1 33 * count: t2/a2 34 * value: a0/a1 35 * We're going to compute 36 * a3 <- countDiff 37 * a2 <- minCount 38 */ 39 subu a3, t2, a2 # a3<- countDiff 40 sleu t7, t2, a2 41 movn a2, t2, t7 # a2<- minCount 42 43 /* 44 * Note: data pointers point to first element. 45 */ 46 addu a0, 16 # point to contents[0] 47 addu a1, 16 # point to contents[0] 48 49 /* Now, build pointers to the string data */ 50 sll t7, t0, 1 # multiply offset by 2 51 addu a0, a0, t7 52 sll t7, t1, 1 # multiply offset by 2 53 addu a1, a1, t7 54 55 /* 56 * At this point we have: 57 * a0: *this string data 58 * a1: *comp string data 59 * a2: iteration count for comparison 60 * a3: value to return if the first part of the string is equal 61 * v0: reserved for result 62 * t0-t5 available for loading string data 63 */ 64 65 subu a2, 2 66 bltz a2, do_remainder2 67 68 /* 69 * Unroll the first two checks so we can quickly catch early mismatch 70 * on long strings (but preserve incoming alignment) 71 */ 72 lhu t0, 0(a0) 73 lhu t1, 0(a1) 74 subu v0, t0, t1 75 beqz v0, 1f 76 RETURN 77 1: 78 lhu t2, 2(a0) 79 lhu t3, 2(a1) 80 subu v0, t2, t3 81 beqz v0, 2f 82 RETURN 83 2: 84 addu a0, 4 # offset to contents[2] 85 addu a1, 4 # offset to contents[2] 86 li t7, 28 87 bgt a2, t7, do_memcmp16 88 subu a2, 3 89 bltz a2, do_remainder 90 91 loopback_triple: 92 lhu t0, 0(a0) 93 lhu t1, 0(a1) 94 subu v0, t0, t1 95 beqz v0, 1f 96 RETURN 97 1: 98 lhu t2, 2(a0) 99 lhu t3, 2(a1) 100 subu v0, t2, t3 101 beqz v0, 2f 102 RETURN 103 2: 104 lhu t4, 4(a0) 105 lhu t5, 4(a1) 106 subu v0, t4, t5 107 beqz v0, 3f 108 RETURN 109 3: 110 addu a0, 6 # offset to contents[i+3] 111 addu a1, 6 # offset to contents[i+3] 112 subu a2, 3 113 bgez a2, loopback_triple 114 115 do_remainder: 116 addu a2, 3 117 beqz a2, returnDiff 118 119 loopback_single: 120 lhu t0, 0(a0) 121 lhu t1, 0(a1) 122 subu v0, t0, t1 123 bnez v0, 1f 124 addu a0, 2 # offset to contents[i+1] 125 addu a1, 2 # offset to contents[i+1] 126 subu a2, 1 127 bnez a2, loopback_single 128 129 returnDiff: 130 move v0, a3 131 1: 132 RETURN 133 134 do_remainder2: 135 addu a2, 2 136 bnez a2, loopback_single 137 move v0, a3 138 RETURN 139 140 /* Long string case */ 141 do_memcmp16: 142 move rOBJ, a3 # save return value if strings are equal 143 JAL(__memcmp16) 144 seq t0, v0, zero 145 movn v0, rOBJ, t0 # overwrite return value if strings are equal 146 RETURN 147
