From f18199c5d0eb133d49eee3b40c795fc716631145 Mon Sep 17 00:00:00 2001
From: PleegWat <pleegwat@telfort.nl>
Date: Thu, 3 Sep 2026 16:45:04 +0200
Subject: [PATCH] Only allow 0o prefix for octal, not just 0

---
 strint.asm      | 53 ++++++++++++++++++++++++-------------------------
 strint_test.asm | 13 ++++++------
 2 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/strint.asm b/strint.asm
index 84bebbc..a807bf2 100644
--- a/strint.asm
+++ b/strint.asm
@@ -1,4 +1,4 @@
-; Internal convention:
+; Internal register assignments:
 ; r1 - Partially parsed output integer
 ; r2 - Parsing position
 ; r3 - Character being parsed
@@ -13,6 +13,7 @@
 ; Clobbers:
 ; flags
 ; r3 - last character read
+; r4 - Negative marker
 ; Note: Unless the input is "0", tail-calls into a base-specific specialization.
 pub atoi:
 mov r2, r1
@@ -23,26 +24,20 @@ cmp r3, 0x2D ; '-'
 jne atoi_positive
 sub r4, zr, 1           ; Set r4 to -1
 add r2, r2, 1
-load_8 r3, [r2]
 atoi_positive:
-cmp r3, 0x30 ; '0'
-jne atoi_dec_loop       ; No prefix, parse decimal
-add r2, r2, 1
-load_8 r3, [r2]         ; From "boxBOX", or an octal digit
-cmp r3, 0x30 ; '0'
-jl atoi_done
-cmp r3, 0x37 ; '7'
-jle atoi_oct_loop       ; Octal with just '0' prefix
-add r2, r2, 1           ; 2-byte prefix 
-and r3, r3, 0x5F        ; to uppercase
-cmp r3, 0x42 ; 'B'
+load_16 r3, [r2]        ; 2-byte prefix "0b", "0o", "0x", etc.
+or r3, r3, 0x20         ; 2nd char to lower case
+add r2, r2, 2
+cmp r3, 0x3062 ; "0b"
 je atoi_bin_loop
-cmp r3, 0x4F ; 'O'
+cmp r3, 0x306F ; "0o"
 je atoi_oct_loop
-cmp r3, 0x58 ; 'X'
+cmp r3, 0x3078 ; "0x"
 je atoi_hex_loop
+sub r2, r2, 2           ; no matching prefix, move pointer back
+jmp atoi_dec_loop
 
-; FALLTHROUGH: not a valid prefix, but we did see a zero
+; Epilogue
 atoi_done:
 add r1, r1, r4          ; If r4 is -1, negate r1. Else it's 0 and no effect.
 xor r1, r1, r4
@@ -58,6 +53,7 @@ jmp r13
 ; Clobbers:
 ; flags
 ; r3 - last character read
+; r4 - Negative marker
 pub atoi_dec:
 mov r2, r1
 mov r1, 0
@@ -76,7 +72,7 @@ cmp r3, 0x39 ; '9'
 jg atoi_done
 add r2, r2, 1
 sub r3, r3, 0x30 ; '0'
-lsl flags, r1, 2
+lsl flags, r1, 2        ; Use flags to help multiply by 10
 add r1, r1, flags
 lsl r1, r1, 1
 add r1, r1, r3
@@ -91,6 +87,7 @@ jmp atoi_dec_loop
 ; Clobbers:
 ; flags
 ; r3 - last character read
+; r4 - Negative marker
 pub atoi_bin:
 mov r2, r1
 mov r1, 0
@@ -102,8 +99,8 @@ sub r4, zr, 1           ; Set r4 to -1
 add r2, r2, 1
 atoi_bin_positive:
 load_16 r3, [r2]        ; check for prefix
-and r3, r3, 0xFF5F      ; to uppercase
-cmp r3, 0x3042 ; "0B"
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x3062 ; "0b"
 jne atoi_bin_loop
 add r2, r2, 2
 atoi_bin_loop:
@@ -127,6 +124,7 @@ jmp atoi_bin_loop
 ; Clobbers:
 ; flags
 ; r3 - last character read
+; r4 - Negative marker
 pub atoi_oct:
 mov r2, r1
 mov r1, 0
@@ -138,8 +136,8 @@ sub r4, zr, 1           ; Set r4 to -1
 add r2, r2, 1
 atoi_oct_positive:
 load_16 r3, [r2]        ; check for prefix
-and r3, r3, 0xFF5F      ; to uppercase
-cmp r3, 0x304F ; "0O"
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x306F ; "0o"
 jne atoi_oct_loop
 add r2, r2, 2
 atoi_oct_loop:
@@ -163,6 +161,7 @@ jmp atoi_oct_loop
 ; Clobbers:
 ; flags
 ; r3 - last character read
+; r4 - Negative marker
 pub atoi_hex:
 mov r2, r1
 mov r1, 0
@@ -174,8 +173,8 @@ sub r4, zr, 1           ; Set r4 to -1
 add r2, r2, 1
 atoi_hex_positive:
 load_16 r3, [r2]        ; check for prefix
-and r3, r3, 0xFF5F      ; to uppercase
-cmp r3, 0x3058 ; "0X"
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x3078 ; "0x"
 jne atoi_oct_loop
 add r2, r2, 2
 atoi_hex_loop:
@@ -191,13 +190,13 @@ add r1, r1, r3
 jmp atoi_hex_loop
 
 atoi_hex_letter:
-and r3, r3, 0x5F ; to uppercase
-cmp r3, 0x41 ; 'A'
+or r3, r3, 0x20 ; to lower case
+cmp r3, 0x61 ; 'a'
 jl atoi_done
-cmp r3, 0x46 ; 'F'
+cmp r3, 0x66 ; 'f'
 jg atoi_done
 add r2, r2, 1
-sub r3, r3, 0x37 ; 'A' - 10
+sub r3, r3, 0x57 ; 'a' - 10
 lsl r1, r1, 4
 add r1, r1, r3
 jmp atoi_hex_loop
diff --git a/strint_test.asm b/strint_test.asm
index 407443b..e44c051 100644
--- a/strint_test.asm
+++ b/strint_test.asm
@@ -46,9 +46,10 @@ tests:
 @0x1040 U32 42          U8 2   "42\0"
 @0x1050 U32 67          U8 2   "67lol\0"
 @0x1060 U32 0x69a       U8 5   "0x69a\0"
-@0x1070 U32 0o23        U8 3   "0239\0"
-@0x1080 U32 0b1011      U8 6   "0b1011\0"
-@0x1090 U32 0b10001     U8 7   "0b100012\0"
-@0x10a0 U32 0xFFFFFFEB  U8 3   "-21\0"       ; Yuk
-@0x10b0
-end_of_tests:
\ No newline at end of file
+@0x1070 U32 0x4B4       U8 5   "0x4B4\0"
+@0x1080 U32 0o23        U8 4   "0o239\0"
+@0x1090 U32 0b1011      U8 6   "0b1011\0"
+@0x10a0 U32 0b10001     U8 7   "0b100012\0"
+@0x10b0 U32 0xFFFFFFEB  U8 3   "-21\0"       ; Yuk
+@0x10c0
+end_of_tests: