From ae5f90456c1e1e0c745c2ffa5ab8add1f0c28d43 Mon Sep 17 00:00:00 2001
From: PleegWat <pleegwat@telfort.nl>
Date: Thu, 10 Sep 2026 21:03:45 +0200
Subject: [PATCH] Add hex

---
 src/int_to_string.asm        | 46 ++++++++++++++++++++++++++++++++++++
 tests/int_to_string_test.asm | 12 +++++++---
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/src/int_to_string.asm b/src/int_to_string.asm
index b67f271..ceb166f 100644
--- a/src/int_to_string.asm
+++ b/src/int_to_string.asm
@@ -15,6 +15,8 @@ cmp r4, 2
 je bin
 cmp r4, 8
 je oct
+cmp r4, 16
+je hex
 mov flags, errno.INTTOSTR_BAD_BASE
 jmp r13
 
@@ -110,3 +112,47 @@ lsr r5, r1, r4          ; Select bit and advance counter
 and r5, r5, 7
 sub r4, r4, 3
 jmp oct_print
+
+; Convert integer to hexadecimal string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4 - input counter
+; r5 - character
+pub hex:
+mov r4, 28
+
+hex_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+
+cmp r4, 0               ; Start printing if last bit ...
+jl hex_print
+cmp r5, zr              ; .. or if nonzero
+je hex_find_one
+
+lsr flags, r5, 2        ; Check buffer size
+add flags, flags, 3
+cmp flags, r3
+ja badbuffer
+
+hex_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+cmp r5, 0x39 ; '9'
+jle hex_no_letter
+add r5, r5, 0x07 ; 'A' - '0' - 10
+hex_no_letter:
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, 0               ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+jmp hex_print
diff --git a/tests/int_to_string_test.asm b/tests/int_to_string_test.asm
index 51a1424..e9b76cd 100644
--- a/tests/int_to_string_test.asm
+++ b/tests/int_to_string_test.asm
@@ -15,6 +15,7 @@ load_8 r4, [r4]
 mov r13, itoa_test_ret  ; return address
 jmp stdlib.int_to_string.auto
 itoa_test_ret:
+nop                     ; For breakpoint after itoa but before r1 clobber
 
 ; Strcmp to check results
 add r1, r8, 5           ; expected output
@@ -44,9 +45,14 @@ tests:
 @0x20000 U32 0b0        U8 2  "0\0"
 @0x20040 U32 0xFFFFFFFF U8 2  "11111111111111111111111111111111\0"
 @0x20080 U32 0b101010   U8 2  "101010\0"
-@0x200c0 U32 0o640      U8 8  "640\0"
-@0x20100 U32 0xFFFFFFFF U8 8  "37777777777\0"
-@0x20140
+@0x200c0 U32 0o0        U8 8  "0\0"
+@0x20100 U32 0o640      U8 8  "640\0"
+@0x20140 U32 0xFFFFFFFF U8 8  "37777777777\0"
+@0x20180 U32 0x0        U8 16 "0\0"
+@0x201c0 U32 0x32fF6    U8 16 "32FF6\0"
+@0x20200 U32 0xdeadbeef U8 16 "DEADBEEF\0"
+@0x20240 U32 0xFFFFFFFF U8 16 "FFFFFFFF\0"
+@0x20280
 end_of_tests:
 scratch: U1024 0