From a1f9e733b83ada52be67c8410c2cf2124af4c94b Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Sat, 13 Jul 2024 21:33:35 -0700
Subject: Digit to String Conversion

---
 dtos.inc | 122 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 dtos.inc

diff --git a/dtos.inc b/dtos.inc
new file mode 100644
index 0000000..fb4a048
--- /dev/null
+++ b/dtos.inc
@@ -0,0 +1,122 @@
+%ifndef DTOS_INC
+%define DTOS_INC
+%ifndef MONAD_INC
+%include "monad.inc"
+%endif
+	
+	section .data
+	_NUMERALS	db	"0123456789ABCDEF"
+	_DATA_BYTE_BUFFER	times 63 db "0"
+	_FIRST_DIGIT	db	"0", 0x0A, 0
+
+	m_make	DTOS_RESULT,	_DATA_BYTE_BUFFER
+
+%macro dtomz_h 1
+	mov	rax,	%1
+	mov	rcx,	16
+	call	data_to_zstring
+%endm
+
+%macro dtomz_d 1
+	mov	rax,	%1
+	mov	rcx,	10
+	call	data_to_zstring
+%endm
+
+%macro dtomz_o 1
+	mov	rax,	%1
+	mov	rcx,	8
+	call	data_to_zstring
+%endm
+
+%macro dtomz_b 1
+	mov	rax,	%1
+	mov	rcx,	2
+	call	data_to_zstring
+%endm
+
+	section .text
+clear_data_zstring:
+	push	rbp
+	mov	rbp,	rsp
+	push	rdi
+	cld
+	lea	rdi,	[rel _DATA_BYTE_BUFFER]
+	mov	al,	"0"
+	mov	rcx,	64
+	rep stosb
+	std
+	pop	rdi
+	mov	rsp,	rbp
+	pop	rbp
+	ret
+
+data_to_zstring:
+	;; rax: Value
+	;; rcx: Base
+	push	rbp
+	mov	rbp,	rsp
+	;;
+	push	rax
+	push	rcx
+	call	clear_data_zstring
+	pop	rcx
+	pop	rax
+
+	cmp	rcx,	16
+	ja	.err_exit
+	cmp	rcx,	2
+	jb	.err_exit
+	std
+	;; Preserve Caller-saved registers
+	push	rsi
+	push	rdi
+	;;  Initially include newline character
+	lea	rdi,	[rel _FIRST_DIGIT]
+.loop:
+	;; Get lowest digit
+	xor	rdx,	rdx
+	div	rcx
+	;; Set the numeral
+	lea	rsi,	[rel _NUMERALS]
+	add	rsi,	rdx
+	movsb
+	cmp	rax,	0
+	jne	.loop
+	mov	rax,	rdi
+	inc	rax
+	cld
+	;; Recover Registers
+	pop	rdi
+	pop	rsi
+	m_return	rel m_DTOS_RESULT,	rax
+	jmp	.exit
+.err_exit:
+	m_Nothing	rel m_DTOS_RESULT
+.exit:
+	lea	rax,	[rel m_DTOS_RESULT]
+	;;
+	mov	rsp,	rbp
+	pop	rbp
+	ret
+
+data_to_zstring_mh:
+	mov	rcx,	16
+	call	data_to_zstring
+	ret
+
+data_to_zstring_md:
+	mov	rcx,	10
+	call	data_to_zstring
+	ret
+
+data_to_zstring_mo:
+	mov	rcx,	8
+	call	data_to_zstring
+	ret
+
+data_to_zstring_mb:
+	mov	rcx,	2
+	call	data_to_zstring
+	ret
+%endif
-- 
cgit v1.2.1