1 /* 2 * String's compareTo. 3 * 4 * Requires r0/r1 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 * r0: this object pointer 15 * r1: comp object pointer 16 * 17 */ 18 19 mov r2, r0 @ this to r2, opening up r0 for return value 20 subs r0, r2, r1 @ Same? 21 bxeq lr 22 23 ldr r4, [r2, #STRING_FIELDOFF_OFFSET] 24 ldr r9, [r1, #STRING_FIELDOFF_OFFSET] 25 ldr r7, [r2, #STRING_FIELDOFF_COUNT] 26 ldr r10, [r1, #STRING_FIELDOFF_COUNT] 27 ldr r2, [r2, #STRING_FIELDOFF_VALUE] 28 ldr r1, [r1, #STRING_FIELDOFF_VALUE] 29 30 /* 31 * At this point, we have: 32 * value: r2/r1 33 * offset: r4/r9 34 * count: r7/r10 35 * We're going to compute 36 * r11 <- countDiff 37 * r10 <- minCount 38 */ 39 subs r11, r7, r10 40 movls r10, r7 41 42 /* Now, build pointers to the string data */ 43 add r2, r2, r4, lsl #1 44 add r1, r1, r9, lsl #1 45 /* 46 * Note: data pointers point to previous element so we can use pre-index 47 * mode with base writeback. 48 */ 49 add r2, #16-2 @ offset to contents[-1] 50 add r1, #16-2 @ offset to contents[-1] 51 52 /* 53 * At this point we have: 54 * r2: *this string data 55 * r1: *comp string data 56 * r10: iteration count for comparison 57 * r11: value to return if the first part of the string is equal 58 * r0: reserved for result 59 * r3, r4, r7, r8, r9, r12 available for loading string data 60 */ 61 62 subs r10, #2 63 blt do_remainder2 64 65 /* 66 * Unroll the first two checks so we can quickly catch early mismatch 67 * on long strings (but preserve incoming alignment) 68 */ 69 70 ldrh r3, [r2, #2]! 71 ldrh r4, [r1, #2]! 72 ldrh r7, [r2, #2]! 73 ldrh r8, [r1, #2]! 74 subs r0, r3, r4 75 subeqs r0, r7, r8 76 bxne lr 77 cmp r10, #28 78 bgt do_memcmp16 79 subs r10, #3 80 blt do_remainder 81 82 loopback_triple: 83 ldrh r3, [r2, #2]! 84 ldrh r4, [r1, #2]! 85 ldrh r7, [r2, #2]! 86 ldrh r8, [r1, #2]! 87 ldrh r9, [r2, #2]! 88 ldrh r12,[r1, #2]! 89 subs r0, r3, r4 90 subeqs r0, r7, r8 91 subeqs r0, r9, r12 92 bxne lr 93 subs r10, #3 94 bge loopback_triple 95 96 do_remainder: 97 adds r10, #3 98 beq returnDiff 99 100 loopback_single: 101 ldrh r3, [r2, #2]! 102 ldrh r4, [r1, #2]! 103 subs r0, r3, r4 104 bxne lr 105 subs r10, #1 106 bne loopback_single 107 108 returnDiff: 109 mov r0, r11 110 bx lr 111 112 do_remainder2: 113 adds r10, #2 114 bne loopback_single 115 mov r0, r11 116 bx lr 117 118 /* Long string case */ 119 do_memcmp16: 120 mov r4, lr 121 ldr lr, .Lmemcmp16 122 mov r7, r11 123 add r0, r2, #2 124 add r1, r1, #2 125 mov r2, r10 126 blx lr 127 cmp r0, #0 128 bxne r4 129 mov r0, r7 130 bx r4 131 132 .Lmemcmp16: 133 .word __memcmp16 134
