From df18adfae7282943e6e0d311cca79a0bee3a3173 Mon Sep 17 00:00:00 2001 From: Clanmaster21 Date: Mon, 21 Oct 2019 02:23:49 +0100 Subject: [PATCH] Moved and indented comment about fmtHex's method --- kernel/core.asm | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/kernel/core.asm b/kernel/core.asm index b612ea6..00f3e96 100644 --- a/kernel/core.asm +++ b/kernel/core.asm @@ -183,17 +183,16 @@ findchar: ; Format the lower nibble of A into a hex char and stores the result in A. -; The idea here is that in the ASCII table, there's 7 characters between -; '9' and 'A', and so we add 7 if the digit is >9. -; daa is designed for using Binary Coded Decimal format, where each -; nibble represents a single base 10 digit. If a nibble has a value -; greater than 9, it adds 6 to that nibble, carrying a 1 to the next -; nibble and bringing the value back between 0-9. This gives us 6 of that -; 7 we needed to add, so then we just condtionally set the carry and -; add that carry, along with a number that maps 0 to '0'. fmtHex: - ; we need to make the upper nibble a known value - ; also clears the N, C and H flags for daa + ; The idea here is that there's 7 characters between '9' and 'A' + ; in the ASCII table, and so we add 7 if the digit is >9. + ; daa is designed for using Binary Coded Decimal format, where each + ; nibble represents a single base 10 digit. If a nibble has a value >9, + ; it adds 6 to that nibble, carrying to the next nibble and bringing the + ; value back between 0-9. This gives us 6 of that 7 we needed to add, so + ; then we just condtionally set the carry and add that carry, along with + ; a number that maps 0 to '0'. We also need the upper nibble to be a + ; set value, and have the N, C and H flags clear. or 0xf0 daa ; now a =0x50 + the original value + 0x06 if >= 0xfa add a, 0xa0 ; cause a carry for the values that were >=0x0a