circom/ports/c/buildasm/sub.asm.ejs

<% function subS1S2() { %>
        xor    rdx, rdx
        mov    edx, eax
        sub    edx, ecx
        jo     sub_manageOverflow   ; rsi already is the 64bits result

        mov    [rdi], rdx       ; not necessary to adjust so just save and return
        ret

sub_manageOverflow:                 ; Do the operation in 64 bits
        push   rsi
        movsx  rsi, eax
        movsx  rdx, ecx
        sub    rsi, rdx
        call   rawCopyS2L
        pop    rsi
        ret
<% } %>

<% function subL1S2(t) { %>
        add rsi, 8
        movsx rdx, ecx
        add rdi, 8
        cmp rdx, 0
        <% const rawSubLabel = global.tmpLabel() %>
        jns <%= rawSubLabel %>
        neg rdx
        call rawAddLS
        sub rdi, 8
        sub rsi, 8
        ret
<%= rawSubLabel %>:
        call rawSubLS
        sub rdi, 8
        sub rsi, 8
        ret
<% } %>


<% function subS1L2(t) { %>
        cmp eax, 0
        <% const s1NegLabel = global.tmpLabel() %>
        js <%= s1NegLabel %>

        ; First Operand is positive
        push rsi
        add rdi, 8
        movsx rsi, eax
        add rdx, 8
        call rawSubSL
        sub rdi, 8
        pop rsi
        ret

<%= s1NegLabel %>:   ; First operand is negative
        push rsi
        lea rsi, [rdx + 8]
        movsx rdx, eax
        add rdi, 8
        neg rdx
        call rawNegLS
        sub rdi, 8
        pop rsi
        ret
<% } %>


<% function subL1L2(t) { %>
        add rdi, 8
        add rsi, 8
        add rdx, 8
        call rawSubLL
        sub rdi, 8
        sub rsi, 8
        ret
<% } %>

;;;;;;;;;;;;;;;;;;;;;;
; sub
;;;;;;;;;;;;;;;;;;;;;;
; Substracts two elements of any kind
; Params:
;   rsi <= Pointer to element 1
;   rdx <= Pointer to element 2
;   rdi <= Pointer to result
; Modified Registers:
;    r8, r9, 10, r11, rax, rcx
;;;;;;;;;;;;;;;;;;;;;;
<%=name%>_sub:
        mov    rax, [rsi]
        mov    rcx, [rdx]
        bt     rax, 63          ; Check if is long first operand
        jc     sub_l1
        bt     rcx, 63          ; Check if is long second operand
        jc     sub_s1l2

sub_s1s2:                       ; Both operands are short
<%=     subS1S2()       %>
sub_l1:
        bt     rcx, 63          ; Check if is short second operand
        jc     sub_l1l2

;;;;;;;;
sub_l1s2:
        bt     rax, 62          ; check if montgomery first
        jc     sub_l1ms2
sub_l1ns2:
<%=     global.setTypeDest("0x80"); %>
<%=     subL1S2(); %>

sub_l1ms2:
        bt     rcx, 62          ; check if montgomery second
        jc     sub_l1ms2m
sub_l1ms2n:
<%=     global.setTypeDest("0xC0"); %>
<%=     global.toMont_b()       %>
<%=     subL1L2()         %>

sub_l1ms2m:
<%=     global.setTypeDest("0xC0"); %>
<%=     subL1L2()         %>


;;;;;;;;
sub_s1l2:
        bt     rcx, 62          ; check if montgomery first
        jc     sub_s1l2m
sub_s1l2n:
<%=     global.setTypeDest("0x80"); %>
<%=     subS1L2(); %>

sub_s1l2m:
        bt     rax, 62          ; check if montgomery second
        jc     sub_s1ml2m
sub_s1nl2m:
<%=     global.setTypeDest("0xC0"); %>
<%=     global.toMont_a()       %>
<%=     subL1L2()         %>

sub_s1ml2m:
<%=     global.setTypeDest("0xC0"); %>
<%=     subL1L2()         %>

;;;;
sub_l1l2:
        bt     rax, 62          ; check if montgomery first
        jc     sub_l1ml2
sub_l1nl2:
        bt     rcx, 62          ; check if montgomery second
        jc     sub_l1nl2m
sub_l1nl2n:
<%=     global.setTypeDest("0x80"); %>
<%=     subL1L2()         %>

sub_l1nl2m:
<%=     global.setTypeDest("0xC0"); %>
<%=     global.toMont_a(); %>
<%=     subL1L2()         %>

sub_l1ml2:
        bt     rcx, 62          ; check if montgomery seconf
        jc     sub_l1ml2m
sub_l1ml2n:
<%=     global.setTypeDest("0xC0"); %>
<%=     global.toMont_b(); %>
<%=     subL1L2()         %>

sub_l1ml2m:
<%=     global.setTypeDest("0xC0"); %>
<%=     subL1L2()         %>


;;;;;;;;;;;;;;;;;;;;;;
; rawSubLS
;;;;;;;;;;;;;;;;;;;;;;
; Substracts a short element from the long element
; Params:
;   rdi <= Pointer to the long data of result
;   rsi <= Pointer to the long data of element 1 where will be substracted
;   rdx <= Value to be substracted
;   [rdi] = [rsi] - rdx
; Modified Registers:
;    rax
;;;;;;;;;;;;;;;;;;;;;;
rawSubLS:
        ; Substract first digit

        mov rax, [rsi]
        sub rax, rdx
        mov [rdi] ,rax
        mov rdx, 0
<% for (let i=1; i<n64; i++) { %>
        mov rax, [rsi + <%=i*8%>]
        sbb rax, rdx
        mov [rdi + <%=i*8%>], rax
<% } %>
        jnc rawSubLS_done   ; if overflow, add q

        ; Add q
rawSubLS_aq:
<% for (let i=0; i<n64; i++) { %>
        mov rax, [q + <%=i*8%>]
        <%= i==0 ? "add" : "adc" %> [rdi + <%=i*8%>], rax
<% } %>
rawSubLS_done:
        ret


;;;;;;;;;;;;;;;;;;;;;;
; rawSubSL
;;;;;;;;;;;;;;;;;;;;;;
; Substracts a long element from a short element
; Params:
;   rdi <= Pointer to the long data of result
;   rsi <= Value from where will bo substracted
;   rdx <= Pointer to long of the value to be substracted
;
;   [rdi] = rsi - [rdx]
; Modified Registers:
;    rax
;;;;;;;;;;;;;;;;;;;;;;
rawSubSL:
        ; Substract first digit
        sub rsi, [rdx]
        mov [rdi] ,rsi

<% for (let i=1; i<n64; i++) { %>
        mov rax, 0
        sbb rax, [rdx + <%=i*8%>]
        mov [rdi + <%=i*8%>], rax
<% } %>
        jnc rawSubSL_done   ; if overflow, add q

        ; Add q
rawSubSL_aq:
<% for (let i=0; i<n64; i++) { %>
        mov rax, [q + <%=i*8%>]
        <%= i==0 ? "add" : "adc" %> [rdi + <%=i*8%>], rax
<% } %>
rawSubSL_done:
        ret

;;;;;;;;;;;;;;;;;;;;;;
; rawSubLL
;;;;;;;;;;;;;;;;;;;;;;
; Substracts a long element from a short element
; Params:
;   rdi <= Pointer to the long data of result
;   rsi <= Pointer to long from where substracted
;   rdx <= Pointer to long of the value to be substracted
;
;   [rdi] = [rsi] - [rdx]
; Modified Registers:
;    rax
;;;;;;;;;;;;;;;;;;;;;;
rawSubLL:
        ; Substract first digit
<% for (let i=0; i<n64; i++) { %>
        mov rax, [rsi + <%=i*8%>]
        <%= i==0 ? "sub" : "sbb" %> rax, [rdx + <%=i*8%>]
        mov [rdi + <%=i*8%>], rax
<% } %>
        jnc rawSubLL_done   ; if overflow, add q

        ; Add q
rawSubLL_aq:
<% for (let i=0; i<n64; i++) { %>
        mov rax, [q + <%=i*8%>]
        <%= i==0 ? "add" : "adc" %> [rdi + <%=i*8%>], rax
<% } %>
rawSubLL_done:
        ret

;;;;;;;;;;;;;;;;;;;;;;
; rawNegLS
;;;;;;;;;;;;;;;;;;;;;;
; Substracts a long element and a short element form 0
; Params:
;   rdi <= Pointer to the long data of result
;   rsi <= Pointer to long from where substracted
;   rdx <= short value to be substracted too
;
;   [rdi] = -[rsi] - rdx
; Modified Registers:
;    rax
;;;;;;;;;;;;;;;;;;;;;;
rawNegLS:
        mov rax, [q]
        sub rax, rdx
        mov [rdi], rax
<% for (let i=1; i<n64; i++) { %>
        mov rax, [q + <%=i*8%> ]
        sbb rax, 0
        mov [rdi + <%=i*8%>], rax
<% } %>
        setc dl

<% for (let i=0; i<n64; i++) { %>
        mov rax, [rdi + <%=i*8%> ]
        <%= i==0 ? "sub" : "sbb" %> rax, [rsi + <%=i*8%>]
        mov [rdi + <%=i*8%>], rax
<% } %>

        setc dh
        or dl, dh
        jz rawNegSL_done

        ; it is a negative value, so add q
<% for (let i=0; i<n64; i++) { %>
        mov rax, [q + <%=i*8%>]
        <%= i==0 ? "add" : "adc" %> [rdi + <%=i*8%>], rax
<% } %>

rawNegSL_done:
        ret